yes they do but to suggest you need have to have one to do the job is not accurate. There are failures from people that used J rollers. Top shops I knew used more white glue and a press.
When i need to know stuff I call pros like techs who make and sell the stuff. They have seen failures from people that use J rollers. This is an assembly table you can go around it and use a rubber mallet strikes then something for internal pressure. If someone cant do that with out having a failure there is some other issue. Or if that is not believed go to home depot and buy one.