The VT is a great knot but takes a lot of time experimenting to find that elusive sweet spot, i always used to dress mine very tight with a 4/1 with the top braid always going over the bottom braid rather than alternate, as I climbed this would ease off to 3 wraps 2 braids, fine for my weight and rope hitch combo.
Also the reason for tieing it tight was to allow the scafold/fishermans?? knots to bed in as they will always creep a bit potentially making the VT you just set perfectly err un-perfect.
Now though i'm climbing on a knute using stiff 10mm ocean cord on Tachyon, what i like about this set-up is its not so fussy/tempremental. Although like any of these hitches they need to be adjusted and dialed in to work for your weight, rope, hitch cord, natural crotch or pulley friction saver la la la. basically what works for one may not work for another.
Back to why i like the knute, I can set the legs of the hitch short reducing sit back to a minimum for a nice positive action, its always easy to advance (especially with 10mm cord on 11.5mm line its just not so bitey) and the 10mm cord on skinny line just doesn't seem to burn my fingers on quick rapid movements in the crown.