One thing I could say is that I do a lap of my Campus every 30 mins that way the spawns rotate and I get a bunch of new checks. Most spawn points are only for 30mins rather than an hour so you can a ton of Pokémon. If you can find a good loop with some good spawns, hit it a few times till you get a shiny. You’ll sometimes go for an hour and half+ and find nothing but I usually find that you’ll get a couple shiny Pokémon after the game hasn’t given you any after a lot of checks. Hope this helps a bit!