You can teach this as part of your set offense. I really liked this off a slow break for a few reasons.
1. The pass is shorter
2. If you are missing a man because he has not joined the play yet you can still execute this. Just take out one of the guys up top or behind. There are much few working parts making these more flexible and more practical in a live situation.
3. Spreading everybody out makes it easy for the ball carrier to see who is open.
4. If a man notices he is uncovered he can cut to the ball through the empty crease area.
As a default I tell my guys to set in a circle every time they start a possession. Once everything is settled they will go into the chosen offense.
However there is a moment between a pure fast break and before the full 6v6 is settled where there is a time to strike.
I try and teach my kids to settle into the open set as quickly as possible then to push that backside immediately. Adjacent slides are difficult to execute when things are organized, this circle set forces an adjacent slide before the defense really has a chance to settle in.
Out of impulse if number 6 drives hard, #4's defender is going to slide to him. This will almost always open up #4 for a back door cut. Like I said, this is tough to identify and defend in a normal 6v6. With the defense not be settled in yet and not having had the opportunity to call there roles that back door cut is almost always open.
If not #6 can either take it himself or kick it back to #5 at X. Now you will find yourself in a standard 2-3-1 set ready to run your 6v6 offense.
This is very low risk high reward as long as the players know not to force it if it is not there. To do this well it should be worked on with your fast breaks during practice. **Up 1 and 1** can easily be modified to work on this.