The biggest factor is how much capillary action the potting mix has – how much horizontal pull. In a cross cut soil diagram, there is always a kind of pyramid starting from the drip point at the top and spreading out as the moisture goes lower. Some mixes have bigger angles than others. Besides the type of potting mix, moisture also influence capillary action. For example, cocoa has a broad angle when moist but a narrow one when dry.
1-3 gallon pot: 1 carrot
5 gallon: 1 carrot + 4 distribution dripper or 2 carrots
10 gallon: 1 maxi, 1 regular carrot plus 5 distribution drippers
20 gallon: 1 maxi, 2 regular carrots plus 5 distribution drippers
30 gallon+: see our BluSoak and large fabric pot kits