Technically, chains don't stretch. They simply wear. And you see a lot of wear in the first hours of use of a new chain. So, if a chain is worn to the point that you need to take a link out, beware that it is not lining up correctly on the clutch sprocket. Each link is slightly longer than the spacing on the sprocket. If you run a badly worn chain for long, you will also wear out the clutch sprocket. If this is the case, you will need a new chain AND a new sprocket. And if you have a sprocket nose bar, that may need to be replaced too. Moral of the story is to never use a chain that is badly worn out.
"Veggie burgers aren't bad if you put enough meat on them"