Or, you really enjoy a hobby but your hyperfocus makes you research the hobby instead of doing it. E.g. you like photography and your hyperfocus kicks in researching places to go take photos, or gear to buy... Or you spend hours choosing the best cycling route until it's too dark or the weather changes and you go "What happened to my beautiful afternoon??".

My hyperfocus tends to kick in whenever the ADHD gremlin inside my brain chooses, not always when I'm doing whatever I enjoy. I wish that was always the case.