I used to shift some stays away from Hilton once I knew I had enough stays/nights to hit Diamond in past years, just to be sure that I would also get mid or higher tier status with 2-3 other chains as well, usually when the Hilton choice was going to cost more than an equivalent from another chain. Otherwise I would continue to stay to get the benefits as others have posted.
This year I'll probably stay far more with Hiltons for the remainder of the year and only try to maintain one other top tier status.