I know this is an older thread but I figured I’d just respond to this one rather than start a new one.
Anyway, I use it for every transplant. It completely eliminates the period of transplant shock and instead of stalling for a week the plants just immediately get the “boom” in growth from being in a bigger pot with more room.
Other than that I honestly can’t say it does much else for my grows. During periods of just regular growth I can’t see any difference between when I do and don’t use it.