It's amazing what you see in a bike workshop. My old boss used to reckon that we should write a book about it. In my opinion it'd get put in the fiction category because nobody would believe it was the truth.
I still remember pulling a tyre and tube off a Raleigh Roadster and discovering that the rim tape was a dressmaker's fabric tape measure stuck down at the valve hole with a piece of Sellotape. At least it HAD a rim tape.
Amazing what you see outside of them as well. I recall taking my bike to get some broken spokes replaced due to London's horrible roads. On riding it home I was struck by a persistent, and distinctly odd bumpy feeling with the rear wheel. Eventually after a couple of miles, I felt I'd narrowed it down to occuring once every revolution.
Looked at the wheel, no vertical or sideways wobble and the tyre seemed seated correctly so I carried on. Eventually there was a hissing sound and a fast deflation of the rear tyre. Pulled it all apart - and found the bikeshop had left me a tyre lever inside the tyre as a gift.
On maintenance v repair - I find it depends on the bike. They all get their tyres pumped up, brakes checked, gears kept in tune - but unless they are regularly going off road and worth some money, I rarely bother with cleaning chains/rest of bike.
If the bike was dirt cheap, I figure I might as well run it into the ground. A 40 quid secondhand commuter bike isn't worth the time on preventative work - especially if I've got a stack of cheap parts in the shed to go on it if something craps out. You'll almost never see me maintaining wheel bearings, bottom brackets etc - I just replace when they fail. A worn out drive chain will last a surprisingly long time before it becomes unusable - and then I'll replace chain, cogs and chainrings all together (again I'm not doing this on expensive bikes, but the 40 quid FB marketplace specials).
I can't abide noisy bikes though so they always get dealt with - even if only with a squirt of gt85 or touch of 3-in-1.
