Basically, you’re stuck with toggling between systems for the advantage of a few pumps, and it doesn’t seem worth it. In the original iteration of this guide, I tested 12 pumps and inflated three different tires completely full to their psi rating, and measured how many pumps it took. Yasuda did similarly for his revamped full-length exploration. That’s 36 tires, and I can guarantee there is no difference between 50 pumps and 100—it’s all terrible.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.
Friction gear systems are a lot simpler to adjust, because the movement of the derailer cable can be modulated as you ride, every time you change the gear- they require less cycle maintenance. Modern index shifting systems are a little more complicated because each ‘click’ must release the exact right amount of cable to allow the derailer to move the correct distance to move the chain from one gear to another. Setting up and adjusting a derailer is not difficult and requires only basic tools, but there is a methodical procedure to follow.