Bam! Your belts break - can't work....
Time spent to change blower belts(me) maybe 2-3 hours and I get to work tomorrow or that afternoon.
Time spent going to JD(disty).
Need to call and make appointment(no walk in's

Idiots!). Next day, no way I get in first thing.
Hopefully that afternoon I get in, drive 45 minutes to an area with way too much traffic.
And wait... How long? Who knows - they never start at appointment time! Half a day and an hour and a half of driving at least.
That's the best case scenario.
What if I can't get in for a day or two? Bad phone calls to make for just being a prima donna and not fixing EASY shat...
You have to know how to do some things.