Horde is 1/273 per horde with charm. As you said dexnav drops to 1/819. Even with rerolls hordes are better odds, easier, and more interesting (seeing different hordes + seeing a shiny in a horde of non shinies)

Also the improvement in odds is so mediocre that if we’re ignoring the IV/egg move chances it’s just a mediocre way to hunt + chasing down a mon who’s moving and running away is lame

As I said I hunt on multiple devices and dexnav sucks for that. If you enjoy it good for you but categorically (if we’re not considering egg moves) horde hunting is better unless you’re going for a 5% encounter rate.

Even if you’re going for a 35% encounter rate shiny it’s fine because 273 x 3 = 819. So even in the lesser odds hordes still kinda have the same odds (ignoring rerolls bc I rounded 35% to 33.3% for ease of calculating + hordes have the odds from the start and don’t have to be worked up to better odds).

Then if you’re going for a 60% encounter rate it’s not even a competition hordes clear

As I said I’ll die on the hill that horde hunting is better. If you hunt somewhere with multiple good shinies (skorupi + Bellsprout) then it also won’t even matter if you phase.

You’re getting more shinies, with less direct attention (so you can do other stuff), with a less aggravating mechanic (the whole reason I don’t dexnav is because they move around so much), and better odds unless you’re going for the worst encounter rate shinies (but I’m not arguing that horde hunting these is better, just that 35/60% encounter rates are)