Has to be every second day, anymore is a waste and can cause damage to your skin, which obviously wont take affect immediately, so tan one day, have a day of none tan, tan, non-tan, tan, non-tan......etc.the mela...... Can't remember the name atm, which is a like a skin pigment cell in your skin, need time to reproduce, otherwise if they can't...thats when it damages them leading to all-sorts of harmful things to the skin
I go for 4 and its done me no harm so far but just be careful :D xx
About once a week because it cost a lot lol, and plus a got skin cancer from it coz I went on 4 times a week I'm all clear off it now but be so so care Full or you will end up like me with horible skin