I like to think of the property market as like the share market in ultra slow motion.
You can't pick the peak of a boom or trough of a bust, so the aim is to buy when prices in an area have a consistent uptrend and sell when there is a consistent downtrend.
At the moment the market across the board is slowing, though there are some areas still rocketing ahead and some basically standing still (anyone seen a suburb/city where prices are currently going backwards?).
So there are still good reasons to continue buying property and not many for selling yet....particularly if after you take your cash out there aren't yet the cheaper properties to buy back into.
Of course, the property market isn't the same as shares so this is a rule of thumb to be modified when common sense/real events dictates otherwise. (I do have a place for sale at the moment, but it was bought specifically to be renoed & traded)
And I do bear in mind the % of income required to cover the loans on properties. Historically this has hung around the 30% mark...when it goes over this (roughly - a few % are sustainable) the market is due for a slowdown & when it's under this the market can sustain a boom....this is impacted by wage levels, inflation, unemployment & interest rates.
Personally I would love to operate in a market like the US which is large enough to have significant booms/busts in different places at the same time. Australia unfortunately shows a tendency due to its small size to all be up or down at once, only at different rates.
Cheers,
Aceyducey