The other rollers do serve a purpose especially if you get a wonky backing or top. You can load them and roll them back & forth to re-square the fabric. They also help keep everything square. Yes, it is a pain to pin it all up but unless you're sure everything is square & is going to stay square. One of the rollers is for your quilt back & I definitely recommend using it. The other is for the quilt top and is optional. Many people prefer to "float" the tops so they can adjust for "wonkiness" as they quilt rather than finding out on the last row just how off the piecing was. Nasty surprise!

Some frames even have a 4th pole for batting which is handy for keeping it off the floor. Both of mine did but I confess that I didn't use it.

Ditto on what others said (leave the leaders on the poles; I baste them to the quilt parts instead of pin); I haven't read all the responses, so this may be a repeat. I had trouble, initially, getting the tubing into the grooves, but finally found that if I started at one end, successfully, and worked all the way to the other end, it went in o.k.

I have 4 rollers on my frame. I am using the two and playing it by ear on the other two.