The short answer: Whatever feels best to you.
The long answer: I believe the largest factor tends to be the goal of your massage therapy session. Not style, or approach, or specific technique, but the goal itself.
I view massage therapy as one massive Venn diagram. There's lot of separate circles (each representing a different approach, style, or technique). But at the heart of it, almost all of those circle overlap each other in significant ways.
Almost all styles of massage are fantastic and offer benefits to those receiving them. At Massage Sci, I focus more on what's typically called a clinical, sports, therapeutic, or medical style, but I also incorporate relaxation techniques, and I often receive those types massages myself as well.
So instead of focusing on a specific style of massage, instead think about what you'd like to accomplish in the session.
I'M HERE BECAUSE X HURTS
When your goal is to address a specific issue, injury, strain, or condition, I recommend a session that includes either 30 minutes or 45 minutes of hands-on time. The session should also include a consultation and after-care recommendations to ensure you have the tools to keep improving outside the therapy office.
That may not sound like a lot of time compared to a "standard" 60 minute massage, but for a massage therapist trained in issue-specific treatments as well as anatomy- and evidence-informed techniques, it's plenty of time.
Muscles can also be "overworked" with massage, which can lead to increased soreness and pain - so simply massaging an area for longer isn't always the best strategy.
Keeping targeted sessions shorter also creates more affordability for repeat visits to stay on top of an issue, instead of starting at zero with too much time in between.
I'M HERE TO CHECK-OUT
When your goal is to just relax, I recommend a session that includes between 45 and 90 minutes of hands-on time.
Where you hold your stress tension, how long it takes for that tension to release, and how long it takes for you to "get in the moment" all contribute to the success of that therapy session.
While you can certainly get therapeutic value out of a relaxation massage (and get relaxation out of a therapeutic massage), when the goal is to ease muscle tension and also relax the body, the amount of time you need depends on how long you feel it may take to achieve that goal.
For some of us, it can take a while for our nervous system to calm down and our constant ticker-tape of tasks and thoughts to slow down. Others may be more practiced and can get into the groove within just a few minutes. - - - In either case, no matter your goal, my best advice is to experiment with a variety of lengths and see what works best for you and the outcomes you need from massage therapy.