Keep Focus Fire up or save for 5 stacks?

[Elleyna]

I finally made the full blown switch to BM but one thing still confuses me a bit and that's when exactly I should be using Focus Fire. I've read guides that say always save it until you have 5 stacks of Frenzy (unless it's about to drop off) and I've also read guides saying to use it to always keep the buff on you, regardless of Frenzy stacks (with exceptions like Stampede and BW). So is there a right answer to this question or is it situational every time I use it? Saving to 5 stacks of Frenzy just feels like it takes absolutely forever at times and it feels like I lose out on potential dps when combining not combing other procs/cooldowns.

[Pundit]

Situational, IMO. There are some fight mechanics that, when they pop up, you'd want every advantage you can get, even if it's not ideal. The start of the very short P3 in Mythic Tectus comes to mind. I'd rather pop 3 stacks and use barrage/beast cleave than wait at that point.

[Elleyna]

Yeah, I guess I get that pretty well, I think my question more or less applies to just standard dps (maybe like Gruul, Oregorger, Hans/Franz, etc) where there aren't any special mechanics really worth saving it for.

[vampiricx]

Azrotharion talks about it in his guide. Basically, use any stacks before BW, if you have 5 stacks and BW is off CD soon, keep them. if BW is not off CD soon, use at 5 stacks.