This was suggested on Discord before, but I think everyone there agreed that right now plant growth fertilizers aren't effective unless you let your plant grow for a month and compare it to a plant grown for the same amount of time without the fertilizer applied.

Growth ferts should be an alternative to when you don't want to acquire larger amounts of the fruit at once, but instead let it keep growing without the constant need of replanting with a double/quad fertilizer.

And a mini suggestion to go with that, maybe get rid of slow growth ferts for plants? They may be useful for pumpkins for when you want to catch them at a certain stage, but do we really need them for plants? They just seem extremely useless and I don't think anyone has ever even used them.