Some dogs just get it faster than others, but we've always used pee-pads for training. You put a pee-pad where they keep going, then start moving it to the door. (I forget frequency and everything, but the instructions are on the package).
With Daisy, when she was a pup, she was in a full size crate, so it was recommended we stick a box in to close off part of it. If the crate is too big, the dog has room to do it's business, then "live" in another part. By making the space smaller, there won't be enough room to do both. The dog won't go to the washroom where she sleeps.
As for the Mastiff pee-ing in the same spot, that's just him/her covering the min-pin's scent.
Hagar:"What kind of dog is that?"
Man with dog:"He's a nice dog!"
Hagar:"You know, at the end of the day, that's always the best kind."