Historically, different SkS/SpS tiers have taken on different rotations, or at least rotational options.
It was normal, for instance, in HW for BLMs to take sufficient SpS to bypass Blizzard IV in a burst rotation, either to finish off a mob, time their more mobile period (as fast-casts are practically wholly mobile due to stutter-step leniency), or sync burst to Raging Strikes (no longer a concern, as it was removed in StB) or Convert. (Before that, even, the big option was actually Piety, as that’d allow you not to mana-shadow while still doing your QuickFlare or full rotation.)
Similarly, a 2.33 GCD DRG often had a superior combination of focus and AoE damage as useful for dungeons because it generated just enough BotD duration (like Enochian, but generating and spending duration with specific skills) to afford an extra Gierskogul (the spender) cast per larger (macro)rotational string without losing the buff, and could handily drop a further spender bonus into the ends of fight when there was sufficient time before the next pull for BotD to come off CD. (Had Gierskogul’s CD been haste-scaled, it likely would have been situationally competitive with the 2.4s GCD build, as it’d be able to get 3 Gierskoguls into Blood for Blood.)
HW’s “Bow Mage”, Monk, and even SMN all saw similar SpS/SkS-driven variances.
Warrior needed a minimum threshold for a “Full-Zerk”, and DRK for its extra Blood Weapon hit, with no further clear tiers thereafter, but it almost always made tanking feel smoother to take a bit more.
This was the double-Death Rune Frost>Blood build for me, back in WotLK (or perhaps even my Blood dps build before others, too, noticed ArP was busted). Sim-wise, it should have been noticeably inferior to Frost>Unholy, but I always parsed higher for my gearscore (“ilvl” now), and often higher regardless.