Because JW preaching is self-reported, there's already nothing to stop JW apologists from counting the time they spend 'preaching' on forums such as this one.
That said, much of the time of 'actual' 'preaching' reported by JWs involves transit rather than actual preaching, especially in rural or semi-rural areas (as well as time spent in a great many coffee shops).
The number of 'peak publishers' is also distorted in JW 'preaching' figures because individuals who fail to report in a particular month can submit two reports the following month, artificially inflating the count.
For all they do to increase the purported number of hours spent 'preaching', it just makes their conversion ratio look worse.