Don't know if I'm missing something, but given that my objective is to maintain (or improve) my hill-climbing shape, I would guess that doing smart trainer workouts specifically designed for climbers is a more efficient use of my time than simply grinding away at simulations of L'Alpe de Huez and the like would be.
That's why I use such workouts, anyway. The software I use has me doing, per week, 1 day of (post-warmup) intervals for about an hour or an hour and a half, followed by an easy day (zones 1 and 2), another day of intervals, and 4 easy days. The intervals are tough but tolerable, with the software occasionally subtly adjusting the resistance mid-interval in accordance with my current heart rate and cadence.
That workout regimen is what it is because I chose (using the software's terminology) "Climber" as my "focus" and an improvement rate of "Slow."
I'm about 2 months in, and my threshold power (which the software recalculates after each workout; no more FTP test torture!) has begun going up by about 1 watt per week.
At that rate, in 5 years my FTP will be . . . !
Edit:
Stole that joke from a book named something like "The Drinker's Cookbook (Lose A Pound A Day For A Year!)" (illustrations by Edward Gorey). I used to own that book but foolishly gave it away at least 40 years ago. The initial recipes in the book used normal-sized type and were complicated; the later recipes were printed in increasingly larger type and became simpler and simpler, with the last few pages being foldouts that used banner-headline fonts.
I used to do searches for the book years ago, but with no success.
New search result: I don't think it's
this, but it might be. Might be a sequel, given the name of this version.