Wait a minute. Riemu, how on earth are you averaging getting 5 BoG stacks with still 10-15 seconds left on EF in 496 gear?
Lets say you're running with DP and you're Haste capped. Your rotation looks like CS - J - X - CS - X - J - CS - X - X, a cycle which would take 9 seconds and generate 5 guaranteed HoPo. Against a boss with a 1.5 second swing timer, you'll face 6 incoming swings in that time. Assuming 33% avoidance (high, but makes the math easy), you'll have 2 "avoids", and thus an average 0.6 GC procs. So that gives you 1.8-1.9 ShoRs per 9 seconds. Thus you'll get, on average, another 0.45 ShoRs from DP procs.
So, Haste capped, running a perfect rotation with 100% time on boss, you're looking at ~2.2 ShoRs per 9 seconds, meaning you can get 5 BoG stacks in 21-22 seconds on average. But that's on average. You might get a couple DP procs in a row or GC procs, letting you get there much faster. But you also might get zero GC or DP procs. You can still reach 5 BoG in 30 seconds, but only if you're Haste capped and playing perfectly. Plus, you lose all your timing flexibility. You need to fire off that EF as soon as you can, regardless of what damage you're taking.
I'm not exactly disagreeing with your approach, just noting that consistently waiting for 5 BoG stacks before firing off the EF might not be nearly as easy as you're suggesting.
Edit - Oh, forgot the most interesting part. When T16 4P comes into play, BoG stack management is a very interesting question. You get the free EF at 3 BoG which doesn't go away when you get BoG stacks 4 and 5. And the extra BoG stacks certainly make *that* EF (and ticks) more powerful.
However, BoG stacks 4 and 5 are taking away "potential" EFs you could be casting for free. If you had cast that EF as soon as you got your free one at 3 BoG stacks, the EF (and its ticks) would be less powerful, but you end up casting 66% more EFs (5 for every 3 you'd cast while waiting for 5 BoG stacks).
Lets think about the math. At 3 BoGs, each EF would directly heal for -40% less than a 5 BoG EF, both on the initial cast as well as each tick. Assuming you keep EF continually running, this means you'll get 40% less HoT healing over the fight which is a lot. On the other hand, instead of casting EF every ~23 seconds, you cast it every 15 seconds. This both likely reduces the overheal from those EFs as well as reduces the likeliness of you getting burst down. If a tank-kill spike damage period averages ~7 seconds, you'll get a big heal every second period instead of every third.