I helped a friend take his mother (PNG Citizen) across to JB for the day. Fortunately he had the sense to bring her return ticket.
On our return we were pulled aside into the secondary clearance area (which is a large room with doors that lock from the outside - you're basically in jail), my car keys seized and we were all told we were under "ICA control". After an hour he was summoned up and he explained he was doing a run and after examining his case he was given 20 days extension for his mother which lined up with her return ticket.
The ICA office essentially said that they will become tighter and tighter on one day turn arounds... and to use the SVP visa extension service in the future or fly/drive out for a reasonable time (> 48 hours he was implying). The officer told him he got the extension BECAUSE he was open about wanting an extension and didn't disguise the reason with some BS about shopping.
I guess we regulars know this but it was interesting and somewhat scary being part of the process. At least I got my car keys back.
My backup plan if he hadn't got her a visa was to U turn back to MY and then drive her up to KL for the next Airniugini flight.