the 3-minute rule is a bit obsolete when you keep heavy-hitterz and large aggressives.......my fish will not fill up in 3 minutes or even 5, so a feed, then a short 10-15 minute waiting period, then repeated until they all get food seems to work well for me. As I stated before, fish feeding in my fishroom can take over 30 minutes or more sometimes.
.....and for good reason, cuz some WILL hog all the food - an assortment of different foods, especially floating AND sinking pellets will make it easier to get food to all the fish