I have been using the Cabela's brand since 1998. I actually have 2 different sizes but use the ones rated for 20ft boat 99% of the time. I have 190hsp Volvo Penta. I run one on each side of the boat tieing off at the bow rail and the stern cleat which makes for quick removal shoud you get a good fish to the side of the boat. I do not know if true or not but a charter captain on Lake O told me always run one on each side of the boat. If you don't you can end up with damage in the outdrive.
We use 1 cabelas sock for a 20 ft boat when it gets really knarly out, right off the side. I generally don't put one out if the water is fairly calm. I can get down to 1.5 using just 1 of the twin 140 on the boat.
My charter captain on lake O had a 27 ft penn yan, he would always use one sock unless it was nasty out then he would go to 2 socks. I chartered with him for a good half dozen years, he taught me everything I needed to know to fish the big O and thats how he ran the socks till he retired.