"Dreamtime is the last part of a player/coach workout when the player decides what to work on."
Dreamtime isn't wasting time, it's using a small part of your developmental time on creative speculation. It might be that time during your workout that you pretend to be 'the guy' (for me that was Sam Jones) taking the critical shot as time wound down. "Too late."
I saw Sam Jones make about fifty perimeter bank shots in a row at his camp (as an NBA retiree). I got to play against Sam (free throws) as the camp free throw champion. I volunteered to go first, because my rationale was that if I could make ten in a row, that would put so much pressure on everyone else that I'd win.
You might work on your dribbling and finishing to be Phil Ford during the delay game.
I didn't call it Dreamtime...I called it "emergency shots". Emergency shots included fallaways, "flyaways" (severe drift), non-dominant hand jumpers, double pump shots, and so forth. Emergency shots constituted about five percent of shooting (e.g. 15 of 300).
I knew these were all "low-quality shots" that my coach called "sh#t shots" but had a place in emergencies. A regular dose of Dreamtime shots would earn you bench time.
Was Dreamtime a waste of time? I took one Dreamtime shot in high school, a double-pump jumper from the left elbow in a sectional championship game that went into overtime. Somehow, it went in, a bad shot with a good result.
Dreamtime forces you to leave your comfort zone and enter an alternative deliberate practice. I encourage you to consider and discuss Dreamtime with your players.