I've had seasons where I am able to observe copulations on a nearly daily basis in both the 32 quart and CB-70 tubs. I've also had seasons where I swear nobody is "getting it on".
Whether I've observed them copulate or not I still rotate them on the same cycle. I sort of take it for granted that they did. The steady rotation provides a little continuity for them. They are secretive creatures to begin with so if you are not seeing hook ups don't feel discouraged - they are probably doing it when you are not around.
I think that if God checked in on Adam and Eve every night to see if they were "hooked up" we probably wouldn't be around. Your snakes will wait for some privacy (read: security) also.
If they have bred for you in the past in the tubs you are using and if they eat and spend the rest of the year in those same tubs (in essence they are not stressed due to the tub) then you should be fine keeping them in the same tubs for breeding this year.
As long as you are still offering water, food on occasion, regular "time outs" away from each other, and proper temperatures/dark periods your pythons will most likely breed - you just don't always see it.