I have been able to put off for quite a while due to dosage decreases.
For any med, it helps to have a cooperative MD over prescribe, particularly if it doesn't make you break pills. Prescribed a drug every other day? Ask for a daily Rx. Prescribed a 50mg dose of something - get an Rx for 100mg. Just be sure to remember your MDs "real" instructions since the label will differ. If you can do this, you will cut your out of pocket.