Typically by using the factory recommended procedure for checking oil levels we don't see many issues from customers. Run engine for a couple of minutes, put it on center stand on LEVEL ground and check sight glass. Halfway between the high and low mark is perfect. It is critical to run it for a couple of minutes and have it on level ground. You cannot check it while running like some engines and you cannot check it properly before it has been run and then shut off.
There is no downside to running a breather overboard I guess except for adding to pollution.