Never was caned, but have been told that even fewer than 9 strokes leaves "marks" and so probably correct that scars may result. Would depend too I assume, if over trousers or trousers &/or undershorts down.
Whether one stroke or 3 strokes is minimum, it obviously was painful. A max of 24 strokes would have to be brutal. The 9 strokes, be it over clothing or bare flesh would leave a bottom marked and sore for days.
The first stroke of the cane will open the skin up in Singapore, the reason being that the strokes of the cane are extremely heavy - the caners are black belt martial arts experts, capable of wielding the cane in such a fashion that the cane breaks the skin on impact. The impact speed is probably right up there with an F1 racing car.
@Jean Michel Cherry well laws are blind cannot always be right. Through out history many many laws has been broken and changed. The law is for good running of society not to ruel it. Using brut for breaking laws and using brut froce on cops is not problems