Johto has several locations where you have to traverse the same area multiple times in order to fully clear them, not for a fun reason (e.g. secret side areas you can't access the first time round; they gain story significance later on in the game; etc.) but just because of ledges and holes.
Route 45 has three paths, each with at least one trainer or item that necessitates its own trip to access. I'm usually pretty desperate for exp at this point in the game, so skipping the trainers isn't an option. If you reach Route 46 for the first time via Route 45 then its forked path won't add any trips beyond the three you're already doing, but I want to point out that if you go there via the Route 31 Dark Cave entrance as soon as you have Strength you'll have to do two loops. The game punishes you for exploring early! The most egregious example is the Ruins of Alph, where completing every puzzle and seeing every message requires you to go through the same part of Union Cave four times.
Yes, this is all optional, but it's still annoying. Unlike a lot of my small Pokemon grievances, it's not even something that only becomes tedious on repeat playthroughs. I think a split path can be really cool if the choice truly feels significant and irreversible, at least until later in the game, but when you can immediately come back and take the alternative route the logical expectation is that the player will just loop around and feel like their time was wasted.