We have loads of issues getting teams prepared for the season, especially with new players and a new style of play. But we can combine special situations into scrimmaging with "O-D-O" three possession games. Because we have thirteen players, we usually scrimmage with three groups - 4, 4, and 5. That also allows different groups to play against each other.
For example:
Free throw (offense) into defense (can be pressure, man-to-man, zone, combinations) then offense with competitive scoring. Offense can work on transition, specific sets, or even delay during its possession(s).
Baseline out of bounds starts the offensive possession. This allows players to practice against live defense and if you want, you can even put in a new BLOB with the defense "naive".
This might have come from CoachPintar.com or not.
Start the sequence (O-D-O) with Sidelines out of bounds (SLOB). I favor BLOBs and SLOBs that can run as independent offensive sets.
You can also initiate the action as an "after time out." For example, assign the defense as maximum pressure and ask the offense to execute "close and late", e.g. down by 2 or 3 with five seconds to go in their own end.
Three possession games offer more realism than some forms of static scrimmaging and permit a lot of flexibility and competitive play. The less teaching interruption during the 'game' the better the flow. The possibilities are myriad.