It really depends. Ability to focus on things you find very interesting in the moment is a presentation that some people exhibit. That might still be an issue even for those things because you can still have high impulsivity, or be very irregular in your interest, or have issues with motivation and executive dysfunction that are separate from that, and of course ADHD affects more than just your work (that's actually a diagnostic criteria).

That the motivational effects of stimulants wear off is not well supported by the evidence. It will definitely feel like they do to you, but your baseline state after the first few weeks is very likely to still be much better than it was before treatment, despite subjectively feeling identical or worse. Of course, it's well established that stimulant medication isn't the only effective thing - controlling distraction is certainly very effective too.