After using a friend's adjustable sticks, one leg of which collapsed just as my shot broke on what should have been a gimme shot on a Gemsbok, I prefer solid sticks. The Gemsbok died but we didn't find it before the coyotes did.
I don't squirrel hunt and can see where adjustable sticks would be advantageous, but for my style of hunting, I have two different lengths of sticks and prefer to pick either standing or sitting sticks when I leave the jeep, depending upon terrain. I have a pretty good idea whether I'll need to shoot standing or sitting and assume proper shooting position to fit the sticks, if that makes sense. Tall grass dictates standing sticks, for instance.
Standard double shooting sticks are very quickly deployed and can be moved quickly by grasping rifle sling and sticks w/weak hand and moving as a unit.
Large coated garden stakes (5/8 or 3/4" diameter) are inexpensive at Lowes, a hank of para chord, some JB Weld, couple of nails or small bolts ground to a point and a piece of dowel can be inserted and glued in the bottom of sticks to prevent slippage. A drop or two of super glue on lashing prevents any slippage of knot.
A bit of ghillie material can even provide a bit of cover and easy mobility when making stands.