I'm a little confused about our rotation at 50. Namely, is flare worth using on a single target?

It seems to me that when our fire spam reaches about ~500 mana or so, we have two options: cast blizzard 3 and start our regen phase, or cast a super hard hitting flare, transpose, and have a longer regen phase.

I almost feel like flares mana cost and cast time make it not worth it, but I'm a fresh 50 so I dunno lol