From a very beginners perspective I expect that it is down to a question of it is confidence, having the equipment & knowing how to do it. I mess about trying to set something up from whatI have, ordering bits, using parts that are not really suitable so they have to be worked on first etc etc.
Its all about having the parts available , knowing what one wants to do with them, having the right equipment set up tools etc & just getting on with the job & not faffing.
for example:-One has to know how to read the dials on the machine. I take ages, checking & double checking because I am not confident. They work perfectly & really i should just be able to wind them in once, do a single adjustment & that is it, job done, but I doubt I would ever get confident enough to do that