I redshirted a senior because my recruiting a gaping hole for the next year and I had 2 equivalent seniors. Killed his WE, but everything else stayed even. Was pretty much maxed out anyway, so not that big a deal. Worked out well but a unique situation I think.
Fuller story: basically had 2 great senior assist PGs but neither great scorers so only really played PG. I couldn't land my target PGs and didn't have any in line on the roster. So I redshirted 1 senior PG with the thought that next year's recruiting season I'd nab a good PG. worked out well as the next year got the PG I wanted, could groom him as 2nd string will my 5th year senior led the team to the tourney.