There is one pic, Laura #526 Ch.45, that you have to say you don't like receiving Ashley pics in Ch.14.
You can pretty much agree to receiving Ashley pics after that in the group chats, even hook up with Ashley, and still get Laura #526.
I don't know if they are exclusive, but there are a handful of Laura "transition" pics that Ashley sends if you reject receiving her (Ashley) pics in Ch.14. The Laura pics from Ashley are much more difficult to get otherwise, because Ashley pretty much sends primarily pics of herself during transitions if you don't reject Ashley pics in Ch.14, and she'll start sending Tara pics if you don't avoid asking for Tara pics in the story...
Other than that, I don't know of any content off the top of my head that is exclusive to a Laura only path...
But, I'm still missing 8 Laura transition pics, so who knows...