ADHD'er here. I am on Ritalin and my kids are on Adderall. I workout in the evenings as well and have had no issues. I do take "medication holidays" on weekends as well (that's what my psych calls them, lol) and they are actually encouraging to that. The Adderall will effect your workout routine and ability and here's why: Adderall is a stimulant. The only dangers of working out on it as an adult is heart rate. If you monitor your heart rate and find it doesn't go extraordinarily high, you should be fine. Will taking your medication holidays make the workouts seem harder to get through? Very possible - again, it's a stimulant. Since it's affecting you AS a stimulant, you may want to ask about Concerta for an option to treat your ADD instead. Then you are able to treat the attention deficit, and not have that stimulant addition. I have to take the stimulant in order to keep myself from jumping cubicles in a single bound,
I actually have to wait for my medication to wear off in order be able to get through my workouts - and I do a LOT more activity on weekends.
I also might add: If you are on Adderall XR and not just plain Adderall, the XR is time released. Therefore it can extend through you longer. So you may think it "should" be out of your system, but it may have lagged sometime during day and held out for later on for you. Just an added piece of knowledge for you
You are doing great and good luck to you!