I do thicker hotcoats than a laminating shop would do to enable me to have a little more margin while sanding, so generally I have to sand my boards a little more to get them down to a good weight, I’d say about 200grams is about the maximum that you can expect to shave off a board with a normal to thick hotcoat (shortboard). 200grams makes a huge difference if the board is already light, but as barry said, if your board is heavy, extra sanding wont make much difference.
easier to save weight with pulling more resin out with the squeegee during lamination, but watch out, too much will leave you with dry spots.
The thing is, if you wet out the cloth adaquately in the first place you would be hard pressed to pull too much resin out of the cloth. I do all epoxy resins these days so I let it puddle up on the side I’m working so it completely fills the cloth. The only time I’m pulling resin out is once all the laps are lapped and fully wetted out. I suspect if using polyesther resins where an operator could force resin into the cloth with a squeege, the potential for dry spots is greater.
I use EPS and epoxy resin. I just made a board with 2 x 6oz glass top and bottom and I did a deck skin of 1/16" balsa. The lams were really dry because I don’t use a lot of resin (often not enough) so I pulled as much off to the sides as I could. I do a generous filler coat to give me something to sand smooth and fill the weave. Before I sand I notice the board feels a bit heavy, and after, I do feel it being more the way I expected it to be. I don’t do a final gloss coat with resin, I usually let the fill coat be the final for the deck. I’ll sand it down a little if needed, but I won’t do another layer of resin. I do a spray finish which I think is lighter than a gloss coat. I sand the rails and bottom to 400 or 600 grit, sometimes 1200 on the rails, or just leave the sprayed finish alone. I like a slightly textured bottom, not glossy smooth.
So depending on how dry your lam is, you could probably loose a little weight. Not sure how much, but I can feel a difference after I sand a board down. And if you do an extra dry lam, be sure to work the filler in and do it at the right time to avoid pinholes. If you get pinholes, you have to add another coat, so you have to work harder, use more resin and probably add weight.