If you know what the task is, hear the reminder to get back on task and still don't get back on task, you need emotional tools. This is beyond a single post, but look for a therapist who can help you with the emotional side of ADHD.
I don't think there has to or should be a long wait. Most infrastructure builds, CI/CD etc are bloated, unoptimized and take too long for no reason.
I completely agree with you on that. However, the wait time is usually not enough for me to really switch tasks for an other "productive" one, because when my pipeline is done, I would just need to switch back, and it really would make it painful.
The option I see about that however, is jotting down ideas for testing later. But then you need to get the time for this optimization, and the optimization will also require you to wait while you test if the result is better.
I know that there is not silver bullet, I'm just trying to make the situation better for me and others in the team