It depends on the size of pots/beds you have, and how much you want to reamend. If you are a commercail cultivator it is always best to get a soil test periodically and reamend based off of the test results.
How much per sqf for reamending beds?
I would start with 1 cup per square foot, and read your plants throughout the following cycle.
Would this work well as a top dressing mix during the cycle as well? Like as a supplemental feed for my garden beds throughout the summer?
This top dress can be used during your cycle as well indoors or outdoors.