That is basically what I am doing, but it takes some trial and error. At least in my case it does. Going off the dashboard charge time to full, is way off the mark in my case anyway.
My car gets driven over the same route on almost every use. The miles driven don't vary by much more than a mile, depending on what we are doing in town.
I started by cutting back on charger time on the timer, then started cutting back on input current to the charger. It wasn't until I have the charge time a 1.5 hr and the input current at 20 amp max, that I have seen any SoC level below 100%. This is with about 25 mile round trips with 20 miles @ 55 mph.
From what I can see from what I have to work with. The battery charges to somewhere between 80-90% at max allowed current, then it starts to taper as the pack approaches full 100%. The idea seam to be to stop charging before the taper.
My situation may not match yours, but regardless of how I charge, I see fluctuation on the GOM when I start in the morning, but fairly consistent miles remaining when I return home. SOC when I return also seams to be fairly consistent when I return also.
Since I don't need to charge for very long, I am reducing the max charge input current so as to charge slower. I plan a once a week equalize charger either on the lowest setting of my level 2 or with the level 1 cord.
I have seen fluctuation on the Kwh used by the charger with the same input setting, I think this is do to the battery charge tapering as it approaches full charge. My goal is to reach the point where the Kwh shown on the charger is relatively consistent and the SoC is less than 100%, somewhere between 80-90%
A lot of trial and error, and changing where and how the car is driven, will change the charge protocol needed to reach my goal.
Whether any of this will have an effect on battery longevity would be hard to tell. Unless you could compare two packs side by side with the same history and the only difference being charging protocol, and then it would only be an indication as there can be variances in cells anyway.