Hi @Jeremy_Corman ,
what you want to know is if the the participants do come back and if so, how often (and maybe for what kind of meeting). Let us assume we use the email address as a unique identifier, we then should tell per email address how often it appears. i apply a variation on the previous formula, this time with email address and this reads as follows.
thisTable.Filter([E-mail].Contains(thisRow.[E-mail])).Count()
numbers are good for stats, so let’s have a look at dates, these are also numbers:
thisTable.Filter([E-mail].Contains(thisRow.[E-mail])).[Match date]
The other thing is maybe you want to know the time between each RDV, I used this formula:
Sequence(1,thisRow.dates.Count()).FormulaMap(
thisRow.dates.Nth(CurrentValue+1) - thisRow.dates.Nth(CurrentValue)
)
With this data in our table and with a different view, maybe you have something of use:
In the suggested approach you can count how many times somebody returned and also within how many days. If you have somebody returning every session, than maybe that is not so good 
I am not sure if this is the way to go for you, but this would be how I would look at my participants.
Let me know how this feels for you, best Christiaan