RPM. Do you mean RoF?

[fresh_k0_lesh]

Is it supposed to be RoF/s. Because that makes the most sense.
Cause if it would be Rounds Per Min, then 0.5 RPM would be useless. Basically 1 missile per 2 mins.

[Palandus]

That depends. We aren't told what amount of time is actually passing as we undergo our fighting. For all we know, each second that passes in the real world, could be one minute in this fictional world. A lot of games do have an accelerated timescale. For example, Skyrim has a accelerated time scale of 20... which means for every 1 minute in the real world, 20 minutes passes in the Skyrim world.

[fresh_k0_lesh]

That depends? Not really.
No matter what default time scale is in this game or similar like RTS games.

If you increase/speed up time, you'll fire faster. For example, if you have a tank that fires every 2 sec, then increasing speed 10x will make it machine gun that fires every 0.2 sec.

That is if fire rate is connected to game time, which is not always the case, but depends on a game, mostly type of it.

There are games that time of the day (ingame) is independent from game gameplay time. Units move/fire, etc faster while actuall time moving at same speed.

Edit:
Considering other game type, that aren't "strategy" type, timescale is basically day/night duration doesn't affect fire rate, moving, etc.