Amendment to section 5.2.1 of the Hv rules (regarding quick-cast spells).

mandatory, but only if the affected player wants it.

Imagine the blue player is affected. If it's done at the player's discretion, the red player makes a full turn, then the blue player makes a full turn, and only then will it become clear that this is a mandatory rest (and in most cases, it will). That is, a lot of time is wasted.