The standard level 50 PLD toolkit can handle pretty much every tankbuster set in the game. It's rare to see tankbusters less than 30 seconds apart, because you're getting into the range where you could start to use one cooldown for two tankbusters. Rock-paper-scissors with Brawler typically is technically 14 seconds for each attachment, but these are not guaranteed tankbusters. Most fights tend to have tankbuster intervals in the 35-60 second range, usually in sets of 3-4 at most before you initiate a phase change or the boss forces a swap. Phase changes typically give you an intermission to recover most (if not all) of your cooldowns.

For single hit tankbusters, it's important to remember to time your cooldown so that the hit lands at the end of the activation period. This shortens the effective recast period. Rampart effectively becomes a 70 second recast and Sentinel effectively becomes a 170 second recast if you do this. It's easy to see why 35+ seconds is a really nice interval in this regard.

Even fights which supposedly "favour" certain MTs don't, really. You don't need Sheltron for Thor or Seph Ex. If you know when the tank busters land and time your cooldowns correctly, you shouldn't run out. Short recast cooldowns like Sheltron and DM are more like icing on the cake. They simply free up other defensive cooldowns so that you can spend more time comfortably tanking out of stance.

In fights with shorter intervals between tankbusters, on the order of 30 seconds, you can comfortably go for two to three minutes on the level 50 PLD kit, depending on whether you include foresight in the mix. The one fight where I could see this to be potentially an issue is unsynced Odin, so maybe you could count that one in favour of WAR's IB.

IB is not without its costs, however. In 2.1-2.5, you would sometimes need to hold onto stacks in order to have it available for a particular tankbuster. In addition, dropping stance cost you stacks, and IB is stance locked. The introduction of Deliverance in 3.0 greatly simplified these issues, but the trade-off is that you're now disincentivized from spending stacks on IB, because of FC.

It's easy to see why RI was added to the kit in HW to fill the 90 second recast slot, but this really only helps for physical fights. ToB works in a pinch, but you get 5% less eHP than Rampart, it increases healing requirements, and its longer recast usually prevents you from using it for alternating tankbusters in a set like you could Rampart/RI.

IB gives WAR's toolkit most of its flexibility, at a cost. This might be an advantage on certain fights if your PLD or DRK only played one job. But a sizeable number of us play the raid slot like Dissidia's Cecil, swapping from PLD to DRK based on the situational advantages of the fight, and the gearing on this raid tier (and likely the next) strongly facilitates this. So there will rarely be a situation where your WAR will have an easier time simultaneously tanking and maximizing their dps than your PLD/DRK.

tl;dr: Don't worry about it. PLD/DRK may require slightly more careful planning on tankbusters on a case by case basis, but simpler is not better.