Even if Jellico was right about it being a superior system, he was still being a shit leader.
You don’t come into a management position and instantly change everything up. You start by learning how things have been going with your staff and setting up a series of changes, with adequate forewarning, for them to adjust to reasonably.
You sure as hell don’t come into a situation that’s tense with time pressures, emotional pressures, legitimate causes to fear for their lives, etc, and then force a wide array of changes onto your staff.
Even if the 4-shift thing is unquestionably superior (and let’s assume it is, ignoring the Bajor comments people are making) - it’s still a stupid as fuck thing to do, under the circumstances.
Especially considering all the other changes and pressures he was adding on, all at the last minute, before a major battle.
Engine overhaul, protocol changes, shift changes, multi-day extreme overtime, on a staff that’s emotionally distressed right before their lives will be put at severe risk?
He’s an absolutely terrible captain and a disgrace to Starfleet. His bullshit would have endangered everyone’s lives for no good reason, had he not been damned lucky that the battle never came.