i've done a few dungeons on BLM for leveling and i'm not level 100 yet, but i haven't had problems with the AF timers being too tight as people keep saying

i can easily do 3 GCDs > paradox > 3gcds > F3 > 2gcds >despair as a "comfort" rotation, but i've also fit 4gcds between refreshes when i had to (especially with triple cast or leylines)