Ir has nothing to do with Danaher but with how I see and probably most people see jiu jitsu. Ive been training for 9 years, and I have always seen very useful to roll with people way below my skill level. It’s where you implement your new attacks, it’s quite simple, it’s the same concept as drilling with progressive resistance. Which IMO, it’s the best way to drill stuff. You are not going to be pulling any single submission or guard pass in a room full of black belts you being a white belt, how are you going to get good at something. You can’t even get started at? Unless guys are letting you do stuff, your not, in which case, you better just find training partners and drill. Also, your Bjj life will suck balls, most people if not all will just quite after 1 year of not Being able to do jack shot but getting smashed. It’s just not fun, it’s hard to keep on training without motivation.
Now I agree that visiting different gyms is extremely beneficial, unless you are in a huge school, that’s what open mats are for.