Use hurry when you need another score and time is scarce; use milk when a running clock protects your lead. Call a timeout before the next snap if you want to prevent runoff.
How much time does each tempo use?
This simulator charges eight seconds for hurry, 22 for normal and 38 for milk before a running-clock snap. The play itself also uses time. Those numbers are game settings, not measured promises for an actual NFL offense.
When does a timeout help?
Use it while the clock is running to stop the next between-play charge. It cannot restore seconds already used. If an incompletion or out-of-bounds finish stopped the clock, a timeout is not needed to prevent runoff in this game.
Does favoring the sideline always stop time?
No. The preference increases the modeled chance of a boundary finish after a positive gain. The historical sample and simulated finish still determine the outcome.
What happens at the two-minute warning?
Runoff that reaches two minutes stops at 2:00 before a snap. If a live play crosses two minutes, the warning is applied at the end of the play. You do not receive lost time back.
Official background: NFL Football Operations rulebook. Exact game timing and simplifications: How it works.