Dont talk cooking now... Im at work.. starving and litteraly watching paint dry...
But lets talk ACMs..

Personally I dont think they have to be perfect. As long as you do use throttle managment, rudder and flaps where it applies. After that if you execute it perfectly or not, who gives a damn.
Seriously.
What I would spend time and focus on is thinking through different situation and thinking:
"Where am I, where do I wana go, how do I get there, when do I wana get there and what does it cost."
This is the most important thinking.
The difference in lost E, time and position between doing the wrong manouver at the wrong time is much much bigger then doing the right manouver perfectly or not so perfectly.
People tend to focus so damn much at conserving E through the manouver instead of thinking of which manouver is better to use.
All the talk about "how do I use rudder and flaps to perfect my flat turn" makes me so ill. I know your not a flat turner but still it kind of shows the example well perfecting something that will give you a performance gain of say 3-4% when there are options that will give you 200% gain with 10s as little effort.
So yeah make sure you do them reasonably well, but then focus on...
"Where am I, where do I wana go, how do I get there, when do I wana get there and what does it cost."
What you should focus on especially in your barrell rolls and your immelmans is controlling the "streach" of them. How do you streach your barrell roll as high as possible, how do you tighten it. Learn to start it tight and then streach it to finish it of wide and vice versa.
Imho the barrellroll is THE most underrated ACM and THE most important one in US (non P38) planes, German Planes and Japanese planes.
Tex.