your plants are old enough you don't need to water so often. this would avoid the problem (except for the aformentioned clear container issues in other answers, if you continue to use those you'll always get it along the sides bc it stays wet enough and gets light).
So, allow the top to dry, then water entire substrate -- same process after transplant too.
if you continue to water as you do, you get more superficial root growth and probably less root mass overall from overwatering (frequency).
always give enough water to wet entirety of soil. a little runoff waste is fine. wait for top 1" to dry (less in a cup) and then repeat. it takes teh volume required to wet entire pot. don't try to pick a volume out of the ether.. it's not your choices. it's a matter of pot size and how long you wait beteen irrigations. if you consistent re-water at same loss of weight / same depth of dryness, it'll require a predictable volume of water.. these factors decide the volume, not us.