The minimum thickness for a professional carom table is 1.77 inches while many are 2 inches thick.
They are heated as well.
Pool tables are far thinner some as little as .75 inches. Each manufacturer can be different.
I played 3 cushion billiards at Chris's in Chicago for years. Never saw any of the 3 cushion tables roll off. Not did any of them need leveling ever. Solid as a rock. There is a significant advantage to thick one piece slate beds on any pool or 3 cushion table.. IMO....
I've seen 3 top of the line billiard tables 'naked' of any cloth and they were all 3 piece slates. Are you aware of any full-sized 3-cushion tables with 2 inch thick slates that are one piece slates? The slate alone would weigh about 1,500 lbs., which seems unlikely.