After a week or so of playing Slayer w/ AM, I agree. It is like a fun mini-game within the rotation and honestly, the cooldown misalignment isn’t as bad as I thought it’d be. Someone on the Skyhold discord said that apparently it’s been theorycrafted that you should hold Bladestorm if Recklessness has less than 24 seconds left on CD, since Reck also has its own cooldown reductions built into our talents and that 24 seconds will be closer to 10-14 seconds, so that’s kind of what I’ve been going with. But of course, it’s all highly situational like you said; if there is a priority add that’s about to spawn that needs to be nuked down ASAP then of course you just full send Bladestorm instead of waiting.
So far am I having a lot of fun with Fury this season, although I’ve only done Undermine so far and haven’t done any M+ yet. That’s where I feel like I will have a bigger decision and adjustment to possibly make regarding Thane vs. Slayer, as last season I played exclusively Slayer for all types of content whereas this season I hear Thane is quite a bit better for M+.