On a steep and rocky descent - the last thing I would do is pull the clutch in ......on a normal bike
I would modulate my speed with front (more) and rear brake (less)
If it was really gnarly I would be in 1st or less gnarly in 2nd
Pulling the clutch in, leaves you out of control and at the mercy of gravity with just brakes to retard the bike, which always ends up out of control imho
As Wreford says - the control is in your legs and feet with your bum as far back as you can get it (on rear brake light) on a descent
Only time I would pull the clutch in on a descent is when stopping to take a photograph
Lock a DCT bike in 1st at the top of the descent if you can and don't ride down without assessing it - maybe walk it first ?