Once again, I am speaking of the M8 and not the M Monochrom which I have never held in my hands.
I made a quick test according to this scenario. I grabbed the camera, started a stop watch, and shot some frames using the continuous mode, lifting my finger off the shutter between all but I think the first two or three consecutive exposures. All the while I was keeping an eye on the watch. As it was closing 15 seconds, I stopped it (at 14.851 seconds). During this time, the camera achieved a total of 13 exposures. Omitting the hour and minute, the DNG files show the following times:
Image 01: 34 seconds
Image 02: 34 seconds
Image 03: 35 seconds
Image 04: 36 seconds
Image 05: 37 seconds
Image 06: 38 seconds
Image 07: 42 seconds
Image 08: 43 seconds
Image 09: 44 seconds
Image 10: 45 seconds
Image 11: 46 seconds
Image 12: 47 seconds
Image 13: 47 seconds
Between images 6 and 7 I shortly paused to simulate a moment of "considering how the composition evolves". The camera did not feel at all unresponsive during the test, it made every exposure when I pushed the shutter, or as fast as the camera can make exposures while keeping the shutter pressed in continuous operation (which I believe is 2fps for 10 shots). After stopping the watch, the memory card light on the camera kept flashing for a while as the buffer was being written to the card. I did not time this flashing. It would have been possible to make more exposures, but the camera is slow for chimping when it writes to card. It needs to clear each image from the buffer to allow viewing it. The SD card is a Sandisk 4GB SDHC card that must be at least 6 years old. The speed/class does not appear on the card.
This test was at about 24C, but the camera works very well in freezing temperatures. It should be noted that the M9 and M Monochrom are slightly slower in continuous shooting, they are rated at 2fps for 8 shots, IIRC. They likely have more or less the same pipeline as M8, but the file size is larger.