it totally depends on your medium, even in soil there is good and bad, like say you had a lot of manure and other organic shit in your soil then you might not need to use nutes for 2 months where as some depleted soil would need them more often, i use coco which has no nutes so i use fox farn at half strength every time as opposed to full strength every other time and i water every 2-3 days and once every week or so ill give them a nice soak with just water, that helps a lot when it comes to buildup, and dont wait until the plant has dried out to water, if the plant wilts at all you lose growth, get a moisture meter and then decide when to water and then you will get a feel for how often you need to water, coc is easy because it holds so much air plus i add perlite that its next to impossible to over water which is a very common problem, but yeah just stick your finger in the dirt half way and if it feels dry then water till some runs out the bottom of the pot