[Tupelo]

“2. It’s fairly normal for about one third of any fleet to spend time in repair and refit.”

I agree. It is my understanding that the subs are out for 6 months per crew. 2 crews per sub. Gold & Blue if memory serves. Then in for repair & refit for 12 to 18 months.
At one time, I read that the navy was thinking of doing the same with the super carriers.

[AndyJackson]

It is my understanding that the subs are out for 6 months per crew. 2 crews per sub.

These are Virgia class attacke subs. Only one crew for an attack boat.

[Right_Wing_Madman]

It is my understanding that the subs are out for 6 months per crew.

Six month deployment for a fast-attack or guided missile submarine (SSN/SSGN) and three month patrol for a ballistic missile submarine (SSBN).