I grow in three gallon fabric pots. I used to topdress every three weeks at the full application rate (tbsp per gallon) and it worked out well. In hind sight it was a lot of fine powder to mix into the soil all at once.
This time around I’ve been trying a weekly application after reading about this methodology from @vincentadultman and indirectly from @alola. Been using 1 tablespoon each week and everything is looking happy and healthy.
You have my attention, and I will check it out.