It depends on the type of boat (Fast-Attack, Ballistic Missile, Cruise Missile), the mission, and the state of world affairs.
FBM submarines are on a 3 month rotation schedule, since they have 2 crews for each boat; the boat spends 1 month for crew transfer and maintenance, then time for sea trials, drills, etc., before heading to their patrol area for several weeks.
Fast-Attacks typically don't have a set schedule - they can be gone for Monday-Friday ops, gone for 2 weeks, 2 months, 4 months, etc. It just depends on the boat's mission at the time, be it actual operations, certifications, training, etc.
Global affairs can alter a boat's mission time as well, or inclement weather like hurricanes which might require an emergencie sortie (underway) from port to avoid the storm.
But no matter how long you're gone, there's always something to do.....
None
Submarines armed with nuclear ballistic missiles
Hitler tried to stop the flow of supplies to England by destroying the convoys of supply ships. He deployed u boats (submarines) with torpedoes to hunt and sink the ships. When he deployed several u boats hunting as a team these were known as wolf packs.
We know one Japanese sub was there for certain; it sunk the carrier Yorktown and destroyer Hamman with one torpedo salvo. Japan deployed about 13 submarines for the Midway operation, including the I-168, which sank Yorktown and Hamman as mentioned above. The U.S. had 19 submarines stationed on patrol lines around Midway but they had little direct impact on the battle.
Usually about a year.
There's a Naval Submarine Base at Point Loma, in San Diego CA. The Navy uses a cyclic system that normally always have at least one Submarine Deployed.
Individuals are deployed on long-term travel to locations that preclude them from filing interim vouchers?
IJN subs were deployed for "fleet warfare", not merchant raiding. The costly job of sinking allied warships fell to the IJN sub fleet. It's estimated that IJN submarines sank less than 50 merchant ships during the war.
Navy SEAL officers can get deployed for as long as 8 to 10 months out of the year, not counting the times that they will be gone for training also.
they can be in different sizes such as being long or short or huge and small
Nuclear Submarines can stay almost indefently for them it is a question of Stores (food). Diesel Submarines are really not designed for under ice operations. AIP Subs can stay submerged for prolonged periods depending on the amount of Liquid Oxygen it has.
Germany made its own submarines and had been doing that since the days of WW 1, long before Hitler.