When one is a pro, things like rounding off bolts make the difference between a profitable job and working extra hours for free to repair what just should have come apart. Many mechs are paid by the hours published in the repair guides, and if it takes them an extra hour or two to do the job they don't get paid extra. On the other hand, if they can beat the book time, they bank extra hours and make more money. As a for instance, my son spent a couple of days working at V3 Jeep Shop in Louisville for his older brother while were were there last week. He banked 22 hours in two days (16 hours of actual on the job time) because he workes faster than the book. He did a clutch on a jeep that booked 4.5 hours and had it done in 2.5 hrs. (yes, he is fast!). He got paid for the 4.5 but was already on another job for the additional 2 hours, literally doubling up his money per hour. He made about $600 in the two days of work. Had he spent the entire day on just the clutch he would have only been paid for the 4.5 hrs, even if it took him 8.
That's why pros have ALL the tools, the BEST tools, and also know just what works where, how to best use air, etc. It's also why they have huge tool boxes, not just for showing off their stuff, but so that they can touch whatever tool they need in seconds instead of digging through drawers that takes minutes or hours per day. Time is money!
I don't have the luxury of a big X huge tool box right now, so my stuff is, well, stuffed. Every drawer is packed full and I do have to do some digging to find what I need. Slows me down, but I'm not getting paid, so whatever. I DO have the stuff... Most everything that one could have on the level of a pro shop with the exception of a few of the large shop-supplied items like a vehicle lift, AC machine (I have portable equipment), transmission flusher, etc. I do have metal-working (inc. welding and fabrication), wood working, electrical and electronic, plumbing, grounds (landscaping), and gunsmithing tools, so I'm well equipped.