I've tried my girlfriend's immediate-release (IR) Adderall. She was prescribed 10mg twice per day when she had an 8-hour workday. I've taken 10 mg once just before work a couple of times, was a bit more productive than normal, and didn't really notice any physical effects. I took 15mg this morning and have been noticeably more productive than usual, still without noticing any physical effects.

Behaviourally, she noticed that I forget to eat and that I tend to hyperfocus. Reduced appetite is very good as long as I don't dip below 25% under my TDEE, but hyperfocusing is a mixed bag. On one hand, it's when I get the most, best (anecdotally) work done. On the other hand, it's pretty draining.