Shipping & Process duration

Appreciate some one could share experience for the shipping duration if as same stated in the shipping calculator. During the covid19 period or before the covid19 period.

Shipment: CJPacket SEA Express KECT00174699 (Delivery time: 3-10 days)
May 05: Place order to CJ
May 13: Parcel received in Shenzhen warehouse. Shipment tracking from CJ website
May 17: Flight depart Shenzhen/ arrive Malaysia same day
May 18: Custom clerance
May 21 (today): NO STATUS from since May 18. Customer still not received

Question
1- After 3 days custom clerance takes so long? That ridicolous to be true.
2- What happen in between May 13 to May 17 (4 days)?
3- Usually how long vendor delivery stock to CJ warehouse?
4- How far usually vendor location to CJ warehouse?
5- How accurate the shipping tracking info?

I was told May 05-May 13 (8 days), CJ had place order to vendor and waiting parcel send to CJ warehouse for precsssing.