I've been helping couples since 2002 and I've learned many valuable lessons on what works and what doesn't.
Starting with the typical model of once a week 45 minute sessions usually doesn't work for most couples needing marriage counseling for a few reasons.
First- It's too short for everyone. These brief sessions don't provide enough time for the couple to fully get to the heart of their issues and it's too short for the therapist to gain a deep understanding of both spouses and their marriage dynamics. Unfortunately, this is a major reason why the success rate for most marriage counseling is mediocre.
Second- Couples are in a crisis. Most couples don't contact a marriage counselor until they are in a state of emergency. One or both spouses are usually considering divorce and they reach out to a marriage therapist as a last hope. Because of these dire circumstances, starting with a 45 minute session usually doesn't come close to providing couples with enough change and hope to heal their relationship in the beginning when they need it most.
Therefore, I highly recommend couples start with either a double (1.5 hours) or half day (3.25 hours) session to provide enough time for the couple to get to the core of their issues, enough time for me to fully understand the dynamics in their marriage, and enough time to make substantial breakthroughs leading to growth and hope right from the start.
After the initial double or half day session, then the standard once a week single (45 minutes) or double (1.5 hours) session is appropriate to help couples continue to modify their relationship and make long-term change. Research shows it usually requires 6 months of weekly sessions before couples start to make substantial progress.