I presume vPost works in this way, they accumulate all items to be shipped from Japan to Singapore for the current week and send it out the following Monday. They save on costs compared to shipping immediately. That's why for those who already paid to vPost this week see estimated delivery of Tuesday till Friday next week. So in other words, you pay the full shipping fees while they still save on shipping by sending in bulk. Just my assumption.
yes possibly so... damn totally not worth it for us consumers.. good for those being delivered today to vpost, maybe still can catch the 'weekly train'

I emailed them, hopefully my order will ship by Monday!