Hi
At the moment both my Mertens and Sandy are getting fed every 2 or 3 days. In winter my Mertens went right off his food to the point where I got so worried that I took him to the vet to see if there was anything wrong with him - at that stage he hadn't eaten for about a month!
He's fine now that the weather has warmed up though.
We only got the Mertens when he was already sub-adult, but as for the Sandy, we were feeding her about every second day when she was a hatchling. Its pretty much just the amounts we are feeding her that we changed, rather than the frequency .
Hope this helps!