Gaining control of the bladder and bowels is a physical maturation process that just takes time. Some puppies develop control a little faster than others. Puppies also have a short attention span so they are easily distracted. One moment they might think they need to pee, they'll get distracted by something, and then suddenly--pee pee emergency!
Reducing the play area your puppy has reduces the amount of area your puppy can make bathroom mistakes in. Puppies don't completely develop object permanence until 12 weeks of age. Babies don't develop object permanence for a long time either. This is why peek-a-boo is so much fun. When you disappear behind your hands, the baby thinks you have genuinely disappeared. They are truly surprised when you reappear from thin air.
Imagine, if a puppy doesn't have object permanence and the pee pee pad isn't visible--the pee pee pad must not exist! Therefore, puppy can pee anywhere! So, make sure the pad is always visible to the puppy to help with training them to go to it on their own.
If the puppy misses the pad slightly by peeing on the edge, don't worry about it at this age. Praise the puppy anyway for going on the pad. Once the puppy is mostly or completely trained to go on pads, you can start placing them in a dog litter pan if you want (as a permanent solution). This is just a flat pan with slightly raised edges so that if they go on the edges, nothing leeks onto the floor.
Also, I'm glad someone liked my masking tape idea. It really works great!
