[Mark McLeod]

There isn't a limit on the number of discrete autonomous routines you write.

You can choose the mode to run from the Driver Station, using the I/O tab, or wired selectors, or by choosing with a button press or a sequence of presses.
You can install a switch on the robot itself to choose between autonomous modes. Switch values are available in your cRIO code. Lots of options.

Choosing Autonomous mode on the Operation tab will just run Autonomous mode as long as it's enabled. No time limit is imposed.

Using Practice mode will by default go through a typical field cycle of Disable/Autonomous/Disable/Teleop/Disable. Options are provided on the Setup tab to adjust the times, so for instance you can reset the Teleop period to be 0 seconds if you don't want to bother with that mode, but still get the Autonomous time limit and other transitions.