It was primarily a case of timing your first Shroud usage to a specific point and time in the fight earlier than was ideal to ensure that your subsequent shrouds aligned with when you wanted to dump Enmity later on. After that first early cast you’d still be using it on cooldown. So it’s less a case of holding it and more a case of remembering to press it earlier than you typically would at the start of the fight.
The way in which the Tankbusters so neatly aligned with shrouds timing after that initial early cast defo makes me think one was designed with the other in mind.