one thing to remember is that even thought the surface is sealed correctly, it doesn't mean you won't ever see absorption. A good sealer will sometimes allow some absorption, but it should go away within an hour or so for the worst cases. So something like straight olive oil might leave a spot after sitting for a while. That will dissipate on it's own, rather than stay. "OMG IT'S BEADING UP!" is not an accurate test of how a sealer is working. They will all bead up after application. You can wipe your forehead and rub it in the stone and it will bead up.
Also, over the years, I have found one thing to be consistent regardless of what sealer have used: if you do 3 applications, or whatever you normally do. You will see far better results by doing that 3rd application 24 hours after the second, rather than doing all 3 the same day.
Each application must be done only after the stone has returned to it's original color from the prior application. If it's still wet, adding a second coat does almost nothing. The second coat can't occupy the same physical space as the 1st coat.
We have a new 2 part sealer in the works right now. It's very similar to what we currently offer, but a little more potent. It will be available in pint, quart and gallon sizes shortly. It's an instant cure formula. It cures in seconds.