Depends how i'm feeling. If i'm just going out an a steady ride and not giving it full beans then it stays where it is, the ride flows better.
But on alot of rides we tend to stop at the top and if its a decent dh coming up lower the saddle and give it some, more of like riding a series of dh's linked by climbs than a flowing ride if you get what I mean..? Drops and jumps aren't too much fun with your seat up.
All depends on what type of rider you are and the terrain you ride.
DH bike saddle stays put at the same height all the time, just low enough not to get in the way when giving it some but high enough so that it can be used to control the bike with the inner thighs…
😀