I made a few bets in the hi-lo game and later in the day I received a second free spin so this theory for receiving more than 1 spin per day appears to be correct.
Well I guess the trigger for the "Wheel" spins are the betting then? I have not received any email for this option and I have been with Freebitco.in for many years. My email is working fine, because I get the other "promotional" emails that they use for advertisements over weekends.
Every promotional email I have received has always included a free wheel spin. It could be that your adblocker is blocking third party trackers and that's why you're not seeing the images you need to click on to redeem the spin.