Potentially controversial and/or dickwagglin' post incoming: Lingering Will is actually easier on Critical than Normal.
Sure you have less health, but the fight's over in pretty much one desperation move, maybe two, as compared to how long it can drag out on Normal. If you get hit you're pretty much up against Once More+Leaf Bracer regardless of if you're playing Normal or Critical, and the shorter fight duration means you get more mileage out of the same number of item slots.
edit: Just to repeat what I said a month back on KH community thread, was having trouble on Normal mode on JP 2.5 Lingering Will since my usual block-block-wait-block-block-reflect combo wasn't working for the desperation move. (Beaten LW countless times prior to 2.5 - suspect that my current setup of whatever has some amount of input->display latency that's throwing me off) I finally fixed that by saving mana for reflect spam, then chugging a mana pot right after. So that goes right back to 'more mileage out of item slots'.