
Originally Posted by
Robby
Brook was with the crew for all a single day before they were scattered for two years, and he still came back as a dedicated forever crew member.
For the crew at least, the amount of time doesn't matter much. For the readers, that's a bit iffier, because yeah just a couple years with the last character instead of 15 feels like a cheat, but we've always had someone joining later than others, and post timeskip especially the crew has been split in half for ages so we haven't gotten focus on lots of them for a while. Zoro and Nami joined in the first few chapters of the series but there's still been a solid 5 years of series one or the other wasn't weren't really in.
The sheer size and reputation of the crew after Wano makes things harder, but its never too late, long as Oda makes them interesting. Even when the series ends its not as if there won't still be anime filler and movies afterwards. Whoever shows up will still get time in the franchise, even when the series ends. Like Mr. Satan, Videl, Goten, and Buu in Dragonball, for instance. They joined in the last 7 volumes, the final two years of Dragonball, (and young Trunks sorta) and they've still gotten exposure for 25 years since. Compared to say Launch, who was around at the start of the series and was just completely forgotten.
Plus, for all that Oda wants to finish in 5 years, its probably not going to be that quick. Long as whoever it is joins *soonish* they're still going to get a few years and a couple of adventures before the end.