on your other thread you asked about getting your paint mare to lower her head when loping and some other issues, and Cherie gave you a detailed explanation of how to push a horse up into the bit. I thought that was rather a good explanation , though a bit different from how dressage riders might explain, I thought it would pertain to this question.
To me, I have contact with the mouth if I am asking for something. So, if I want the horse to step leftward, slow down, give at the poll, back up, move up to the bit and collect, bend toward something, and various other reasons, I take up contact. If I dont' need to do any oof those things, I am happy to have no contact at all, if the hrose can carry that and be trusted to not bolt or whatever. I have rope reins that are very easy to shorten rather quickly, so I let them drape down whenever possible.
I always say that contact is ok, but it must be meaningful and the horse must always have a way to earn relief from the contact. So, you have a reason to have contact and yo9u are communicating something, and once the horse listens and responds correctly, they earn relieve from the contact.
Cherie , in her other post, was talking about setting your hands and driveing the horse forward into the bit, and the horse finds his own releif from the contact by kind of "bouncing" off the bit and flexing at the poll. In which case, you keep your hands steady and quiet and in the same place, only opening your fingers ever so slightly to say "yes, thankyou for coming up to the bit and please stay here".