I believe the key is finding a generic contractor (supervisor) who is reliable and scrupulous, responsible and at the same time experienced in the construction

I believe the key is finding a generic contractor (supervisor) who is reliable and scrupulous, responsible and at the same time experienced in the construction industry practices, not afraid of quarrel and confrontation with shady contractors. Money helps as motivator and allows not to rush things through but alone is not a guarantee. Lots of independent and diverse professionals and groups with own agenda and attitude need to act in symphony to produce a satisfactory result. Not an easy feast, despite of the collective wisdom accumulated throughout the centuries construction quality suffers in most cases, to a varying degree, occupants need to get used to and ignore troubles avoidable for long long time in theory (and in practice too with the proper care).