Potential is what it is - it won't change unless your players drop some points and go back to having average potential, but that would only occur if the current rating changed, not due to a change in potential (this could sound a little confusing, but in an attempt to clarify potential may be considered to mean the amount of growth remaining or the cap level at which a skill is maxed out). Given literally all reds I'd probably put about 10 minutes into everything. Anything for which you get a maxed out e-mail from your assistant you can drop and put into anything that still seems to be growing a bit. Low potential (red) can mean anything from 0 to 6 points worth of potential growth remaining. Start out with everything even and try to work more minutes into the categories that look to be closer to the 6 end of things.