I'm not a fan of them, especially in the spring. Lot better choices to drag behind the boat, but like just about anything with a hook on it, will catch a rockfish at some point in time. Before planer boards we used to pull them fairly deep in the fall season with success. Only real benefit compared to an umbrella is they create less drag when pulling in a fish. As the rockfish numbers continue to decline I feel its more important to go with the proven baits that are more likely to produce results. Tandem Chutes, a few Single Chutes, and Umbrellas, throw in a Tony on the WWB and add a little patience and your good to go.
Hard to explain but they run hot / cold - sorta like big spoons do.
Some years daisy chains are the ticket - other years hardly worth pulling.
I will say - when they do get hit , often a quality fish. I've had some high 40's and just 50 inchers hit them.
I build my own - often store bought use wire as leader. I prefer 80 lb mono for the daisy part ( teasers ) stopping at a swivel. This allows me to use a short 12-24 inch leader that I can easily change if it chafes. I use 1/8 to 1/2 oz Sea Witches as teasers - with a bead / crimp to hold them about 12-18 inches apart. Chartreuse outfishes white 5 to 1 for me.
Store bought are often one piece leader - you have to cut it back to retie the lure knot.
I run them off board or real deep with a down rigger or wire line / 20 oz MoJo tandem.