I don't like it. Years ago when I worked in a pool hall I'd go practice there and then go to whichever bar league was at that night and it was totally horrible. I found myself winning more often without shooting on the 9' beforehand.
Actually a little more of a change, I warmed up on a snooker table before going gamble on bar boxes, did this from the time I tried a snooker table.
I had a small time hustler staying with me for a few days. I took him to my practice hall and got the snooker rack. He fought with the snooker table mightily but after about forty-five minutes he was making a few balls.
We played on the snooker table for about another hour then headed for the action tables. Rod got on a bar table before I did and I was watching when he started shooting. He pocketed the very first ball, looked up at me and grinned. I just said "yeah", no explanation needed of why we worked out on the snooker table. The pockets on a bar table looked like #3 washtubs!
A small caveat: You do have to play on the bar table enough to be able to swap back and forth easily to the different playing balls, rails, cloth, and pockets. As long as you do that the big table will help you with pocketing, speed control, position play, pretty much everything but actually breaking up problems but when you can do everything else breaking up problems isn't an issue.
If it's 9 ball I like to practice on 9 footers but for 8 ball I stick to practicing on the barbox. I spread them way better on the 9 footer so I don't have nearly as many clusters to try to deal with. I'm probably one of the few that feels like 8 ball is tougher on a barbox but I'm not nearly as good as many here lol.
Practice long shots on the 9 footer or snooker table, it will help you focus on your shot making on the 7 footer, BUT don't run balls where you're positioning yourself for the next shot on the bigger table cause this will mess up your speed control on the smaller table.