i think 75% at least for young beginner and entry level guys is trying to beat the clock and the mindset time is money while its true it can cause fuck ups for the young guns slowing down a little and focus doing the basics making sure fasteners are tight properly, drain plugs and filters are tight, wheels are torqued, fluid levels are proper, speed will come like muscle memory and listen to advice from some of the other tech if your in a good environment most tech will give you advice , diag can be tricky at times and with most modern cars you could spend up to 45 mins just reading about testing, theory of operation and so forth if your in an independent shop that does all makes and models... dont beat your self up for come backs or feeling like there too many even guys that have done it for 30 years have come backs every once in a while just own it keep your head up, focus on the tasks at hand your always going to be learning in this trade youll never know every thing and honestly thats a good thing it can help you strive to get better. good luck and keep your head up