Second coats on similar colors are almost never recogicnized as being needed until the coat is applied and has dried. ONLY THEN WILL YOU SEE WHETHER IT NEEDS A SECOND COAT or not. Yes, painters can use a cheaper paint then what you paid for. That is solved by getting your own which, I would charge extra for because I will always have to go get more, or add second coat because home owner tried to skimp on paint, or they got the wrong color etc...
I made the HUGE mistake of hiring Certa Pro to do several interior rooms of my house, and remove popcorn ceiling in a bathroom. What a nightmare! They didn't paint any door jams, they broke a cedar window sill-and didn't bother telling me, they gouged a hardwood floor, they never sealed the room that had the popcorn removed--causing white powder to be in all rooms of a 2 story home. I can go on and on. Horrible company
Wow, I learned so much. Now I know why I got the cost quote I got to do the job right. Being a cook I get it... because you can't just make a meatloaf... you can't just paint a room. You better know what you are doing and the cost of a GREAT job is like the right cut of meat. So, you can look at th finished product and smile & enjoy... great job !!
Not only careful communication is essential, but we would greatly recommend, when you pick out your type and brand of paint that you go and pay for it, with the contractor's discount, which is given by Sherwin-Williams and most paint companies. Then you will know how much paint you purchased and the coverage. If it is possible, inspect the work of the painter daily.