Ok so I also have the same issue. It makes scheduled recordings almost useless. How incredibly frustrating to miss the last 2 mins of all my shows. Usually the most important part.
I fortunately found you can go in and edit the end time. But it would be sooo much easier if you could just set a single setting to extend all recordings. This seems an essential setting for any recording scheduler. It’s almost like the Webos creators haven’t used this feature!