I'm a proud former Royal Navy Marine Engineering Artificer (Technician) so I was well trained as an apprentice through journeymans time and throughout my career to fix and maintain some pretty big industrial kit. That kind of thing never leaves you, so when I do any vehicle maintenance I tend to replace anything and everything that is a source of failure or appears to be less than 100%.
It may well be like triggers broom, but I'd hate calling breakdown or pushing the bike home, or pulling the brake lever and nothing happens.