If using an 18MB, you can fire cues at 1/100th of a second from module to module. If using an 18MA, you can fire cues at 1/10th of a second.
If you are manually firing, the 18M will fire as fast as your fingers can press the 18R2 cue buttons, even allowing you to press multiple buttons at the same time.
Please note that when firing one cue after another on the same module it is recommended that you do not fire a subsequent cue on the same module for the full fire time.
For example, If you are firing Talon/Clip-on Igniters, while you could go from one module to another up to 1/100th of a second after another, you will want to wait a full two seconds before firing another cue on the same module. This is recommended as it prevents a shorted igniter from causing a subsequent cue to not fire.
If you are firing e-Match or MJG initiators the recommendation is the same, but keeping it to 1/10th of a second after another on the same module as this is the fire time when the module is in e-Match mode.
Once again, you can fire from one module to another as fast as 1/100th of a second with hardware B or 1/10th with hardware A, however, please note that this pertains to single script files.
When a multi-script file is used only the first script on the file can fire at the above specifications. Subsequent scripts are restricted to firing with more than a 0.4s delay from module to module.