BTW; This is what friends have told me so please don't jump on me for it.
I have a few friends that have stayed up to 6 months without being checked upon, others longer but it seems the general one is every 3 months, they leave Cyprus for a weekend then come back, then your waiting time to join starts again. Not sure of the wait before you join though.
However, if you were born in another country that wasn’t Greece or Cyprus e.g. the UK, you can obtain a letter from your COB or council stating that you are a Brit citizen; you only have to serve something like 6 months. A friend of mine did that, join in January and is out at the end of this month, seems like he is laughing huh