The trapshooting pros take your kind of approach. They would go into a quite mode about 10 minutes before their turn and watch targets that are being shot and work on their breathing and eye exercise and do some stretches. I heard a commentator said that Biado was doing push ups and sit ups right before his match in the US Open finals. All you need is to get the muscles warmed up. A pro will learn nothing new on a practice table. Practice time on the actual table you will be playing on is of course useful to get a feel for the table.Not that this is so for the pros, but some of the "penny ante" tournaments I go to, some guys want to practice the whole time before their match. Wont let anyone else get some swings in on the limited practice tables they have. I dont worry about it. I usually beat those guys anyway.
Getting in stroke is 99% mental anyway. I spend my time before a match grooming the mental side. Put the earbuds in, get relaxed, and listen to subliminal messages or self hypnosis recordings. Some of you may think its garbage, but I assure you I dont go to the table tense or apprehensive. My percentages show my best chance for a B&R (8 ball) is the first or second game.
I heard that Shane practice 3 hours before he plays. I think this is a bad thing because it can cause mental fatigue mostly as he gets older. A calm brain is your friend in any sport.