Theres probably a lot of reasons why fish go deep,and when they stay deep fishing isn't that great.When I used to ice fish,a few guys had flasher units they would put in the holes, you could watch deep fish ignore baits. But let them come up a few feet, and it could turn into a zoo at feeding time. I believe light conditions had a lot to do with that. Even on a blue bird day, If I wasn't up to trolling I'd anchor on the windiest side of the lake, and catcj something,but that was due to plankton and bait fish following the food into shallow dingy water.Heres something I used to check, major fishing events tried to coincide with "best fishing days",these can be planned weeks ahead of times, but a weather event could put the wjammy on it sometimes.