My gearing combinations change to suit my fitness and preference to stay in the sweet spot of my 7-speed freewheels and cassettes -- the middle three cogs. Outside of those cogs, drivetrain friction increases a bit. Or maybe I just feel slower when I can hear the drivetrain at all.
When I got my '89 Ironman in 2017 I rode it with the standard 52/42 chainrings and 13-24 freewheel. But -- unbeknownst to me at the time -- an old thyroid condition was worsening and I was gradually getting weaker. At the time I just figured "Meh, I'm getting older." So I switched to the Vuelta 50/39 chainrings and SunRace 13-25 freewheel, which kept me in the sweet spot most of the time.
Fast forward, turns out I had thyroid cancer, then I was hit by a car, so all of 2018 and much of 2019 was a recovery period. Then then I'd switched the Ironman to a 50/38 Vuelta double, because I'd gotten so weak it was tough to climb even with a 38 chainring and 28 rear cog. Some days I needed my Univega hybrid with 50/40/30 triple and 11-32 cassette, just to crawl up modest hills in the 30/32 combo. Some days even that was hard.
By spring 2019 I mostly switched to a new-to-me 1993 Trek 5900 bought from another BF member, and rode that 90% of the time until January this year. I used it with a 52/42 Biopace double, which doesn't really feel like 52/42 round rings. The eccentric Biopace sorta feel like 50/39 with a bit of extra leverage oomph during the power part of the stroke, if I'm in a bigger gear and slower cadence. I mostly paired that with wheelsets with 7-speed 13-28 freewheels or cassettes -- no problems switching, no need for derailleur adjustments.
Anyway, by January 2020 that Trek needed an overhaul -- especially the headset, but also the bottom bracket, etc. So it's been disassembled awaiting parts (trying to keep the original Chris King and White Industries components as much as possible).
I switched back to the Ironman and have ridden it almost exclusively this year, other than my hybrids for errands. Discovered I was regaining some strength and fitness and the 50/38 chainring didn't feel right anymore. I switched to the 52/42 Biopace for a few weeks but it didn't feel quite right with the 172.5 Suntour cranks so I swapped to the 170mm Shimano cranks. Better, but... now I'm back to the original 52T Suntour big ring (plain, not ramped and pinned) and 39T Vuelta plain small ring, with 13-28 freewheels until both rear rims cracked (hey, they lasted 30+ years, between me and previous owners). Now I'm on a borrowed rear wheel with 7-speed 12-32 cassette, which feels odd. Big jumps in spacing with only 7 cogs stretched across 12-32. But I'm mostly in the sweet spot of the middle three cogs, so it's okay.
Subject to change at whim and inevitable age related decline in fitness. Those 50T and 38T Vuelta rings will eventually find their way back onto a bike.
A friend is persuading me to test ride a Klein Quantum with 44/32 chainring. That should be interesting. I hadn't thought about buying a Klein or any aluminum bike, but this might change my mind. We'll see after a few rides. Especially if it'll handle 700x28 tires.