Yeah, it’s probably more British slang more than anything. To “bang in” or “knock in” or “pan in” or “put in” a quantity of anything is generally used to describe a tedious or repetitive task.

One could “knock in a good few hours of revision” or “bang in half hour on the treadmill” or “put in a shitload of effort” or other such terms.

In this case, my lad plays Pokémon Go, but I’ll cover distance goals to accelerate progress a bit.