If Oda had stuck to his original plan...

[Captain Cadaver]

And ended the series within 5 years as he originally planned, going purely with the ideas already outlined and cutting out any he thought of along the way, how would that affect the series for you?

"I was going to finish ONE PIECE within 5 years. Every crew joins before Grand Line. (1- 1.5 year) Great adventure (3 years) Final arc (1 year)" Sound Recording (2012)

Source: https://aminoapps.com/c/anime/page/blog/interviews-with-oda-his-editors/x2t2_u6n4Mxql7EBgaPzlrQvaxZ8oV

Info on ideas Oda improvised: https://comicbook.com/anime/2018/08/18/one-piece-creator-last-minute-plot-points-revealed/

Basically, that cuts out a lot of ideas such as Lucci being a villain, Ace being Roger's son or the Supernovas in general.

Personally, I think it would've been for the better to have condensed the journey down to that of a medium length Shonen series. Whilst it'd mean cutting out some ideas and locations that helped liven up the world, OP's overall writing quality between arcs has been fairly inconsistent since Alabasta and has just been going downhill since the timeskip due to Oda's inability to develop characters past their initial arc in favour of maintaining the status-quo or extending many portions of the series for the sake of mystery bait have severely damaged the series in the long term. Streamlining the series down to that of a ~25 volume manga, with him sticking with ideas from Romance Dawn such as making the Shichibukai and Yonko just one group, would've made for a more concise, fast paced story that didn't allow for the problems of its static characters or overuse of Shonen cliches and mystery to become as egregious as they currently are.

We would miss out on cool things such as the CP9 plot twist and severe changes to Marineford, though considering the lack of importance a lot of them ended up playing in terms of the bigger picture, it'd be an acceptable loss.

 

[Notaka]

Five years seems a little low for me tbh. 10-15 years, on the other, I agree could wrap up things neatly.

However, let's say One Piece ran for 5 years. How many arcs would there be? If he said 3 years for the adventure, that's equivalent to around 157 chapters. You can say that's enough to fit around 5 arcs worth 30 chapters for the great adventure. You could make more arcs by having them take less chapters, just as you can make less but longer arcs. But if he went either route, he'd either look like he's rushing the storyline in the former or that it won't really feel much of an adventure if they only visited a handful of islands in the latter.

It would also take away some of the world building aspect, something I like about and praise One Piece for, should he have done the five years route. Like the road to becoming a pirate king is supposed to be long and arduous and Luffy becomes the next one by visiting only a handful of islands?(Assuming he becomes the king, though.)

However, Oda could make it work if he actually had five years. Either way, I'm going to lay down my opinion:

Yes, it would. If he did it in five years, I wouldn't like One Piece as much as I do now and perhaps would have never watched/read it. It being long kinda makes you get the feel of an adventure. But, like I said, if he wanted to end it, ten to fifteen years are sufficient enough imo.