It's fun to watch the insertion count over the process. Insertions don't mean hair count because some hairs need a second blast, but it gives you a decent idea of how fast she is and what was accomplished in a session. She can make a file for you and then print out the statistics for you to take home.
If you look on the screen of the XCELL Pro, you can see the insertion count. It is located in the upper part of the right hand corner. After I clear someone's chin, I can look on the screen and tell the client how many insertions were made. I also give them a copy of the stats to keep after each session. Very cool and high tech. Here is an example of what I give my clients after a treatment: