@amenonsen @anna entering Singapore:
Exit at Malaysian border control, scan out
Bus waits for everyone to get out and board (also good time to pee)
Crosses the bridge to Singapore, everyone get out again this time with all bags
Scan out (most who do this regularly have some expedited status that lets them use the machines, otherwise there are also border agents who can stamp in)
Everyone boards again (this takes longer as Singapore enters the bus to check throughout for contraband, and some people may also have issue crossing)
When everyone boards again they leave towards the drop off point in Singapore.
Pretty much the same in the other direction