Enshroud is actually pretty rigid in terms of how it gets used in practice under two-minute burst, unless you're playing freestyle. You want to fit two Enshrouds into an Arcane Circle window, which means that you specifically have to enter your two-minute burst with 50 shroud and 9 seconds left on Death's Design. This is because Enshroud has a 15 second recast, while Arcane Circle only lasts for 20 seconds. So you have to have your first Enshroud occur at least 5 seconds before you Arcane Circle. Those 'other' GCDs action choices that you're going on about? Yeah, Shadow of Death and Harvest Moon, which are your options, are specifically there to buy time to let 5 seconds of recast tick off. You're not using them for fun. Likewise, Communio's cast generally syncs up with mechanic checks, which may require you to make clever use of Ingress/Egress on the fly.

No, the thing that makes Enshroud's design interesting is the fact that you have control over where you place your 1 minute mini-burst for a potential Triple Enshroud, which in turn requires you to understand how your kit interacts with fight mechanics.