Somebody from a Travel Agency in Penang who organizes VISA Runs on a daily basis has told me that you can get up to 3 SETV's/year from there, on the same passport. With all the extensions that makes 9 months/year. On the other hand, the consulate in Penang told me that, because I already had 6 SETVs and 2 VOA's in my 3 yr old passport (that's an average of 2 SETV/year), I might get a red-flag the next time I apply for a SETV. This leads me to believe that, by average, 2 SETV's/year is the optimal number permitted that raises no eyebrows. (unless you have other Visa Exempt Stamps or VOA's)