Question for the brain trust:

This past saturday i had 3 separate instances while sight casting reds I would barely miss a school by a foot or 2 and I'd end up catching a trout. This was a first for me.  I've heard mickey talk about large trout following schools of bull reds before. These were mostly all slot fish in these instances but the question still stands; Is this a seasonal thing? A conditions thing? For extra context i was a little bit deeper than normal, water was very dirty, they were on shrimp, and the schools were moving a lot faster than what i'm used to seeing. Was a pleasant suprise until i hooked a 12" trout and he blew up the biggest school of the day