I'm not sure I can tell the difference between when I did and now, to be honest. If there is a difference, it's so negligible that I'm not sure it's worth the effort.

I just do whatever trimming I'm going to do and then hit it with the rub.

I know there's been debate about bone in or bone out. I've used the Costco packs so often now I don't remember the last time I did one that still had the bone in it. I have discovered that one of the things I like about the bone out shoulders is that I can hold it open and sprinkle my rub all around inside the space where the bone was removed. I like that I can get some of the rub flavoring inside the meat and not just on the outside.

Anyway - to the original question - I wouldn't worry about it too much. Try it if you like. Don't if you don't. I'm not sure you'll notice enough of a difference to worry over it too much.