The design of the table can dictate the thickness of a table top.
A harvest table may have 1 1/2" or thicker top.
A top for a Duncan Phyfe table may be only 3/4".
You should always adhere to the original design to some degree to keep the table from looking home made. You start to feel you're finally getting pretty good as a furniture maker when your work no longer looks home made.
A quick I D of the furniture you've made yourself by a novice is no compliment.
If you don't have time to do it right the first time, when will you have time to do it over?