Feeding with a pail makes heifers into your best friends. Feeding with auto feeders just makes you into a possible predator when you try to walk amongst them. My neighbor feeds entirely with auto feeders, he has about 10 of the big 10 ton+ feeders, all Hereford cattle, and all complete nutjobs when you walk amongst them. He insists I walk through them each time I visit, to show how fancy (lardy fat ready for the hook) they are. All I notice is how fast they run to the other end of the pen and think how depressing it would be to be around such flighty animals every day.
Feeding steers would be different, because they have a rapidly approaching expiry date, but heifers you want for breeding need a little more attention to make them into special cows. Unless your training for the Olympics during calving season.