Summoner need a lot management if the fight have downtime

[Eclipse12187]

Too much spell speed causes Bahamut and Phoenix to misalign with party wide raid buffs.

[Sunako]

Too much spell speed causes Bahamut and Phoenix to misalign with party wide raid buffs.

Does it matter? you can use your summons with raidbuff then, it is better than losing couple thousand potency, because of downtime.

[Warlyx]

Too much spell speed causes Bahamut and Phoenix to misalign with party wide raid buffs.

happens on Ex2 if u use buff+baha on add phase and dont use phoenix until boss comes again

[Sunako]

happens on Ex2 if u use buff+baha on add phase and dont use phoenix until boss comes again

If you check timeline what people have done in the extreme. Pretty much every single top summoner have used akh morn and death flare before add phase and used Searing Light during add phase without Bahamut. It worth using Bahamut even if you can just throw akh morn and death flare into it.