I believe the dinks are higher in the water column, so you catch more of them 1st, then you'll be able to get down past them to the better fish.
Hickory Nut & I will pull up to a spot, catch several smaller fish before we catch a quality slab. We have often discussed this subject and the thought train that if your catching little fish, you should move.
We definitely don't play by that rule here in this general area. We have caught lot's of great fish off the same spot that we caught smaller ones off of, but if you want to only target BIG SLABS, then yes move to the timber, you'll still catch smaller fish, but your size ratio will go up, but your catch ratio will diminish greatly.
There's my 2 cents for what it's worth