don't forget that adding more lube means your switches will attract more dust. use lube as sparingly as possible, i would say that the amount you use is just as dependent on how often you apply it becase like i said, it's not exactly going anywhere. it may slooooooowly break down over time but we're talking years, you might not even be using the same board / switches for that long (unless you're an ibm nerd).
obviously that's not hard and fast but face facts: we're fickle and we switch up our keyboards a lot. most people who use the same mech for years and years dont give a crap about lubing, they're also very likely not 'enthusiasts' but people who found a board they liked and moved onto more important things.