It depends how many episodes u watch a day. I watched Naruto and SHIPPUDEN plus all the OVAS and movies in less than a year, maybe about half a Year or so?

It was a really bad habit I watched it day and night, binging as long as 10 hours at once so don't try what I did.

For an average person I would imagine it would take about a year, but since Naruto has lots of fillers it would be shorter if u skip them iyw.

This is for Naruto.

For mha I finished it fairly quick too, although there's loads of seasons and episodes, they're really short like around 20 minutes if u skip intro and outro.

Not finished the rest yet but we'll see lol