On single entry depending where you are from , is 30 days as norm. You can extend up to 90 days with interval between 30 days each for a short run of about 5 days to JB, Bali whatever. Best to come in thru Changi Airport or you can go to
www.ica.gov.sg to extend it if you intend not to do the short run.Your visa will be renewed in between the run or going on line
Either way max is 90 days . If you exceed this , you be asked to leave OR if you continuing doing those run, you may end up being banned from SG.
Just make sure you have sufficient funds to survive here like CC or cash or someone living in SG that can vouch you as Immigration Officer might query you in between those runs.
Thread carefully
The positive thinker sees the invisible, feels the intangible, and achieves the impossible.Yahoo !!!