sorry overread that one.. Or thought i already answered it in a ticket. Too much Joomla! work at the moment
Feel free to ping me with any questions on Glip btw.
The reason we have a fourth page is, that there also the online payment for for example paypal is taking place. And mails are only sent after that notification. There is actually a setting for activating direct mails after the third page, but this can cause sending duplicate mails.
On my todo-list for 6.0.0 there was actually a new banner (better looking) with 4 steps, so people don't see that payment step as actual optional, when they pay cash, by cheque etc.
As we use the common payment API by techjoomla and everyone can write plugins on their own i don't see a nice way sending emails for plugins like cheque or purchase order or cash already after the third one
Hate that behavior too..