Action- Add Crow Form to casting unit

I've read quite a few jump spell tutorials over the last year, but there is one thing that alwways struck me.

You add, and then remove Crow Form in the trigger, because having the skill at one point in the game will forever give the unit the required changeable flying height.

But wouldn't putting crow form in a disabled spellbook give the same effect, since it is only the spellbook that is disabled, not Crow Form.

I do understand that adding and removing Crow Form can be useful for "throw" spell where you have no idea which units will be targeted, but when there is only one or a handful of units, why add those extra line in the trigger?

If there is only one or a handful of units you can just add/remove it once and never bother about it again (barring reports I've seen before of ensnare/entangle stopping it working, not sure if those are accurate or not though).

Wow, I definitely thought you were WILL.

The thread on the ensnare debate can be found here.