I have a simple rule for turnbacks.
If I pass 600~800 ft AGL on the upwind/crosswind leg I will try it depending on percentage of power lost and strength of downwind. Anything less than 500ft I'll consider it EFATO (look straight ahead for emergency landing)
Also I always keep in mind where the crosswind (if any) is coming from so that in case something go's wrong I'll turn towards wind to minimize the turn radius towards the runway.
In cases where the departure/pattern crosswind leg is downwind for the wind blowing that day I
A) try to delay a bit the 500ft turn (to gain height up to 700~800)
or
B) cheat the pattern (my ground track) off a bit towards to the direction of the wind blowing
... so that I can make it (glide) back to the downwind runway in case of turnback.
Choice of A) or B) depend on local topology like populated areas, terrain etc.
In the aircraft I fly (TB20) with gear retracted on downwind, abeam the touch down point I need 1200~1300ft AGL to glide to it.