I think with Nathan/Haley's wedding and Brooke/Julian's wedding, there wasn't really anything else going on that took up a lot of screen time or distracted away from the wedding, so everyone was just focused on that and so they made a set time for the speeches and for all of the characters to be sat down and everything. LP's wedding seemed a lot more casual as it was really rushed what with Peyton being pregnant, so I don't think anyone would've really had much time to write speeches. Heck even Haley had to pretty much make hers up on the spot. Plus they had a lot of other drama going on (tbh, I was more interested in the Brooke/Julian stuff in that episode), plus there was Skills/Lauren/Jamie and Nathan/Haley and then Mia singing. If they had had more time then speeches would've been cool but I wouldn't have wanted them to cut out other characters plots or time for it, especially when season 6 was really quite LP-heavy.