Solid Hardwood, Engineered and Laminate Flooring - sealer/primer before varathaning floors?

I was preparing to do my own hardwood floors, but got delayed and now there's a time deadline that I can't meet doing it myself, and I caved in and am hiring a pro.
He wants to use 3 coats of sealer and 2 coats of varathane. I haven't read anywhere on this forum of using sealer, so I suggested to him that I probably want 3 coats of varathane. He will do it, for a small amount extra (due to the extra sanding involved).
He said that the sealer prevents the wood grain from raising, meaning no sanding, and no resulting dust to settle in the varathane. It's also less time. I told him that no web forum that I had read mentioned sealer, and was wondering if this was merely a shortcut that ultimately cheapened the job?!
Do I want 3 sealer plus 2 varathane, or 3 coats of only varathane?
Thanks!
(p.s. next time I will do the floors myself, honestly.)

Each coat of polyurethane is a sealer unto itself.
BTW, verathane is simply Flecto's name for polyurethane. The varathane I'm familiar with is oil base and won't raise the grain.
Maybe they make a waterbase varathane now, not sure.
Out of curiosity I would ask your contractor what is the sealer he would be using?? What does it contain?

Let's see - 3 sealer, 2 poly. And he wants extra for just 3 poly coats only.

There is always dust from sanding between coats. It takes good preparation and clean-up to do a floor successfully.

I'd go with three coats of poly................
fred

To begin with I don't know of a floor finish for sanded floors that you apply without abrading the floor before final coating. Their is no extra sanding needed for Flecto Varethane waterbase finish. The manufacturer has in its info that you can put multiple coats of Varethane on with no abrading in between but that you must abrade floor before final coat. Sounds like he was saying 3 total coats of sealer. First coat sealer and 2 coats varethane. Their is more labor and material cost to put 3 coats of sealer. Instead of a first coat of Varethane. The reason for using a sealer on open grain wood floors is. On your first coat almost any sealer or polyurethane is mostly sucked up by the wood and seals the wood.

We have used varathane by customer request on a few occasions. Don't like their waterbased. Oil worked ok but we screened vac and tacked between all the coats and it has held up well. Something just bugged me about not screening between coats like we usually do.

Phil