That's far past conservative...
In multiple ways.
For example wouldn't really want to think about flying with below 40% charge in cold weather.
Overall lithium chemistry simply likes middle voltages of cell:
Charging always to full charge puts notable extra wear compared to say 80% charge.
High voltage kick starts one degradation process and increasing temperature gives further speed to chemical processes.
Again low charge/cell voltage kick starts another degradation process.
In fact unless actually needing max endurance, you shouldn't regularly push lithium batteries to full 100% charge.
And full charge/high cell voltage storage is torture for lithium chemistry.
For scale getting that last 10% of charge capacity for full 100% charge like halves the achievable cycle count untill certain capacity loss from wear.
Protections are there simply to prevent critically/fast dangerous charge levels, not to give battery long life time.
Electric cars actually avoid that "normal" 100% charge and have differently calibrated charge scale to slow down loss of capacity over cycles.
And depth of discharge is another factor.
80% discharges wears battery lot faster than doing 50% discharges.
So there's plenty of range in usage of lithium batteries depending on your flying needs and what battery wear speed you accept.
Agreed & your comments on LiPo Chemistry is correct... Different from other battery chemistry, Middle voltage optimal operation voltage, ambient temperature has an direct impact on LiPo discharge & storage (like many other battery chemistry), Regular application of High C (amperage) charge & discharge increases rate of LiPo Gel decay.
Comparison to electric car design is a bit skewed but understand your comparison in behavior characteristics of battery chemistry. Although battery volume / capacity, chemistry and charging is very different. Car’s… specifically Telsa regarding their mega charging is not recommended for normal charging… Telsa states it’s more for traveling or specific needs and is reconized to accelerate the wear & decay of battery cell. That goes along with High Amperage / High Voltage charging increases decay of chemicals. The capacity shares similarity in max capacity stored has an impact… although not as impacting as small RC LiPo due to chemistry differences, designs not nearly as constrained to size & weight, and programming by design in cars that indicates 100% much lower than true capacity.
That all recognized, the majority of Tesla Owners charge at mega chargers vs home 110/240v low Amp chargers. Most charge to full capacity if time allows… more often than partial to reduce the number of times needing to sit at a charging station; the gas station mentality to ”Fill Up” is maintained.
Regarding the RC LiPo pack, specifically the DJI smart IC LiPo Pak… percentage is not an accurate measure of capacity or voltages that effect Chemistry, the FW matrix can display any percentage to voltage desired. Although it is accurate, the longer duration discharges impacts LiPo Gel… 80% discharge creates more chemical activity than 50 or 30% discharge… simple chemistry dynamics.
Although the design of the Pak: Size limitations, Capacity, Voltage / Cells and Chemistry composition was “designed“ to provide full discharge within the FW’s percentage scale (again not a direct corleation to max, avg, minimal voltages). The chemical design including gel capacity was provided to meet desired flight times with a calculated Life Span of Battery.
Using the battery significantly under the designed specifications can increase length of life. Similar to any power unit used below the minimal side of the intended maximum of design will increase length of life. A gas motor driven without hard acceleration, prevention to generate high torque, prevent RPM’s from going into upper RPM curve, etc can increase the life of the power unit. BUT won’t achieve the designed performance that may have been intended in purchase.
The Practice of battery discharge and flight time is wide spread and debated with many opposing views. Although that doesn’t mean one is bad practice and other good practice. It does indicate one end of practice doesn’t utilize the battery design limits as much as other extreme end of practice. The lighter use practice may increase the battery life span.
Battery Life span, several variables: A LiPo Battery’s Gel decays without any external variables… LiPo’s will decay sitting in box on shelf over extended time period… the Gel Chemistry has an active lifespan.
A Battery‘s LiPo Gel decay does have a correlation to battery cycles & duration (depth) of discharge within the cycle. Although NOT as impactful as POOR Battery Treatment: storage, temps, charge practice and flight operations. After battery discharge, recharging hot gel greatly impacts the chemistry, storing in areas of high heat: direct sunlight, trunk of car, etc will impact gel chemistry, loose storage allowing batteries to bounce about in container, extended storing at lower single digit percentage (near minimal voltage). The “Treatment Practice” can impact overall life span greater than “Duration of discharge”. A new battery can be quickly decayed below functional operation without using the battery by exposing to heat & sunlight heat.
Regarding the practice of discharge: If a Hobbyist, times can be very short, any practice can be adopted. If flying a Construction Grid or Survey, objective is longer duration of discharge, flying profession set cinematography productions, cold weather operations, Industry Inspections often require regular mission near maximum duration, or flying SAR missions, the need for maximum discharge is often applied with rapid recharge turn-around of multiple Battery sets.
Although contrary to expressed minimal light usage; Heavily stressed battery operations, the Battery will endure close to the life span & number charge cycles of a battery practice of minimal flight time & minimal discharge. The design of the battery provides much more duration using a battery 80% Charged and ended at 40% charge, although that provides an unsatisfactory short flight time for several types of Professional Missions.
I’ve monitored my M600Pro Platform‘s TB48 batteries (6 per flight) carry heavy payloads, land below 14% consistently, cold, heat & humidity and fully charged to maximum level multiple times a day endure years of service without loosing time on flights. Batteries are decaying per the properties of LiPo Gel within design... that an acceptable known outcome.
