How do I know how many times my male dog has to pee to actually empty his bladder if all he does is tiny amounts of marking a million times? Is there any way to encourage them to actually pee rather than just marking?

We have a new one year old shepherd mix who seemed relatively house broken when we got him, or at least no accidents for the first 3 or 4 days. But now he's had two accidents for some reason. The last one was especially weird because we had just come in from a walk and he must have peed at least twenty times or more, but it's always only just a tiny drizzle. He was getting a little wound up playing with tennis balls in the house with us when he suddenly stopped mid play and just peed a much larger amount, no leg lift like usual. Not sure if he got over excited or what. Is there any way we can encourage him to actually empty his bladder outside rather than just marking everything? I've been rewarding the outside peeing but he's obviously not actually emptying his bladder. But he's had no trouble going through the night like 9 hours without peeing and he does the same thing when I take him out in the morning, just tiny amounts of pee a million times. So I have no idea when to take him back inside.