Sinkie ah long dun operate like HK ah long where debt can snowball and interests charge on interests.
Typical sinkie ah long loan lets say 1k loan you get 800 upfront and over next 5 weeks you pay 200 per installment.
Simple enough 20% interests.
Only get interesting when you are late or miss the weekly payments.
It's 200 per week 'interests' if you cannot make payment on time. Technically debt won't snowball, it's just that you seemed never be able to finish paying off the 1k loan that's all.
That's when other stalls enter the picture and the more stalls you loan from the more your debts ballon.