I am going to throw out some ideas.
First I have not listened much to Dream Theater.
When I go to design/create a preset, I think about how the tonalities will work with and against what I am using it for. That has to do with how the drummer/percussionist is tuned and how they play. If they are busy player, that will eat up a lot of apace. I have think about how the bass is voiced, and the vocal range of the singer. I also have to think about how I have my guitar dialed in, and what type of od/dirt/fuzz I am using. I then eq and manipulate the repeats of a delay to find a sweet spot.
I also then have to take into consideration how I will be playing. For example, if I am going to use less notes per measure, and play very melodically, I then have space for more stuff to be happening. If I am ripping out 16th notes or 16th note triplets, that will not give much room for any repeats.
I typically end up more in the slap range of time, because I tend to get excited and play fast. If I am trying to move out of the slap range of time, I end up typically using less repeats, and like my delay repeats to become darker.
I am just throwing these ideas out, to show that there is a way to think about these questions.
When I step back and listen, I can hear how well something works. It is the same as listening for what chord is taking place, or what scale is being used.
I like to think about as, when I listen analytically to the stuff music theory names/describes, I think about pitch. When I listen to timbre/tone color, I think about It as frequencies. Same thing but a little different focus.
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