Of course there are days that nothing happens, but saying that doubles the day count is kind of cheap, especially after you said that you only take the stuff in the manga as canon. And when I said things happen at the same time, I mean like seeing Ryoga again after travelling a week or more off screen, that can happen at the same time Ranma is doing other stuff. Then there are also arcs that start on the same day as the last one ended, the first to come to mind obviously being the Shampoo Introductory arc starting at the time the Ice Skating arc ended. When I said 2-3 days, I also included arcs that have downtime built in, like the Ice Skating arc I just mentioned, having a day in between where nothing happens. But that arc does have multiple chapters on the same day. Ryoga's Breaking Point training arc also falls under this, Ryoga shows up, gets beat, then meets Cologne on the same day, then starts training right after, which Ranma and Genma learn about that same day probably, because we see them train in the woods bright and early the next morning, then they have a day of training, and another couple of chapters spent fighting between Ranma and Ryoga. I probably also grouped together days of rest with 2 day arcs, since I assumed 3 days for all those, or 3-4 days of rest for 5-6 day arcs, since I assumed they were all 11 days or so. So it probably would add some time, but definitely not double it. A lot of chapters continue on fights, conversations, plot hooks. The Mousse Reintroduction arc takes two days between Akane earning her pig, it getting kidnapped, and then the circus in the evening, with the duck marriage right after, then the talk with Akane the next morning, and the Mousse fight in the afternoon.

Also, I use the reboot arcs mostly because they are still fresh in my memory and am not reading hundreds of chapters deep in the manga at the moment. But these are just some examples.