That's a lie, training in groups is the absolute worst.
Waiting for others to catch their Pokemon while you're wasting precious time on your Incense just standing there.
Trying to decide on a route to take.
Others whose GPS functions differently and they can tag Pokestops from further away then you.
And then you've got all the dumb rumors that have hopefully died out by now like:
"Oh, tap the Pokeball if you miss to get it back!"
"If you track a Pokemon and the thing pulses blue, you're headed in the right direction!"
"I saw the silhouette of [insert Pokemon not currently in the game here] the other day!"
Also, for those still using the terrible Pokevision website, this is the best thing I've found so far: https://github.com/mchristopher/PokemonGo-DesktopMap/releases
Do you use a dummy account for this or can you log in with your main PTC account?