Ive used Sealer and Glaze two times, under Meguiar's Gold Class, it helps a lot, it really brings out the luster in the paint. But make sure you dont apply it to a hot surface, otherwise it would leave a haze, tried it on the bonnet on my datsun, it left such a bad haze that it wouldnt go away, had to wait for it to cool down and then waxed it to remove the haze.
Sealer and Glaze once every two months is perfectly fine.