This is all fair, for sure, there's just never a situation where you should run into that problem, if you've been properly rotating cooldowns. At the *very least* you'll still have Foresight, Rampart's ugly little brother that nobody wants to talk to. Most times it'll be ramp > sen > ramp > hg > ramp > sen > ramp > ???????? (with Sheltron for each if they're physical) and it's really rare that you'll encounter a fight that throws that much shit at you to actually make all of your stuff be on cooldown, assuming you handle stuff properly. As a last ditch effort to save yourself from a mistake, yeah, but in general, you shouldn't be stacking Sheltron and Bulwark. Like... except in that very -very- rare circumstance you just lined up.
The 3-minute cooldown on Bulwark is definitely annoying as hell. It feels like a niche utility cooldown, but it's way too long to be used like that. You basically need to use it when you need/want a string of consistent blocks and almost have to work your cooldown rotation around it, because of how long its timer is.
Like in A1S, I would roll (since I didn't tank that fight in ShO, even for the buster) Awareness and 10-15s later Foresight after each buster to keep my incoming damage more consistent through the final runoff before the jump, since it's likely to die to that final cleave. I *WISH* I could have used Bulwark there, too, but it was a 2-minute spread, not 3-minute, so Bulwark could be used once, but not the second time. :\
It's a matter of usage. You don't use "redundant" the same way you use "useless." Synonyms aren't always interchangeable. :0redundant
rɪˈdʌnd(ə)nt/
adjective
not or no longer needed or useful; superfluous.
The Redundant Department of Redundancies Department doesn't have nearly the same punny meaning as the Useless Department of Uselessness Department, for example.