How do you know when the floor is finished (sanding poly etc) ?

We recently bought a house that has original pine floors. Our GC sanded the floors once and covered it with one coat of poly and one coat of laceur. The floor to be looks very unfinished to me. One part had been under carpets for years and is not congruent with the other parts. I have heard that flloors need a minimum of 3 coats of poly with sanding in between. Our GC considers the floors done.

Can someone tell me what is the norm for finishing pine floors – how many coats required. What should the finished floor look like ?

In addition, if someone could recommend a company to give an estimate of leftoverwork to be done, and to help us do it, this would be much appreciated.