An on the record decision is when a claimant is awarded disability benefits on the basis of the record (strong medical records) without the need for a formal hearing.
Normally on the record decisions are requested when a claimant has further compelling medical records, those records should be included at the same time when the request is made for the on the record review.
In some hearing offices, but not all, judges will try to weed out the cases they can easily grant because the medical evidence is so strong.
Some judges never grant on-the-record decisions, and if you are assigned to one of those judges, there’s not much you can do but wait for the hearing.
Personally I would never request an on the record without legal council, if you have an attorney, I would certainly speak to him/her about the process as it can really speed things up.
If an attorney is quite confident they will win the case, they normally won't have a problem requesting an OTR decision.
Depending on your situation, you may also request to file for dire needs.
Please see the SSA website for more details on that subject.
Good luck to you