don't forget that you only have 4.5 sec until you can proc 'ppa' again and you will use fb multiple times in a row until you get it...and yes i agree, dps mercs do currently have no place in ranked wzs.
I disagree with the first statement. Unfortunately we agree on the second.
The use of FB continously until RS is procc'ed is not efficient. There comes a time when using FB actually decreases the expected frequency of RS attacks. For example, suppose your RS cooldown has 1.5 seconds remaining. Using FB at this point is rather dubious, because if it procs RS you don't get a RS attack any sooner, and you lose the chance for a quick RS-RP-RS sequence. Correspondingly if RS is on cooldown with 3.0 seconds remaining, a successful RS proc gives you one RS attack in the next 7.5 seconds, but waiting 3.0 seconds (and using other abilities) gives you a 60% chance for TWO RS attacks in the next 7.5 seconds. Even with 4.5 seconds on your RS CD, the expected number of RS attacks decreases if you use FB - although here the tactical situation (heat, health remaining on target, etc.) dictates whether you want to attempt front loading your RS attacks. Bottom line though is that you do NOT want to use FB indescriminately.