That’s a great question, and the answer is certainly “it depends.” And it depends on many things like your goals, your schedule, your recovery status, etc. Mainly, though, I’d like to suggest that you take what you can get (or give yourself) in this life and if you can only get 2-3 sessions per week, then that’s great. Research supports that even this amount can produce outstanding training effects and that’s been my experience over the years with many clients. You can be pretty doggone healthy and fit off that amount. However, when your goals get a little “zesty” and you really want to attack and crush serious goals, 5-6 days per week are better. Adding to this, I’d say training 7 days per week and doing 2-a-days can also have a place, but frankly the younger and more serious and accomplished athletes do best with this model. In summary, just do what you can most of the time and then try to have a couple periods a year when you get after it a bit more.