The short window helps reduce any delays in your research/experiments due to a strain arriving in poor health or a non-viable condition. Rather than spending your own time trying to recover a sick or dead strain and putting your experiments or research on hold hoping to revive it, notifying us within 48 hours will allow us to troubleshoot and ship a replacement to you with our next shipment group--typically the following Monday. 

Also, it becomes increasingly difficult as time passes to determine the cause of any issues with strain viability, which would have allowed us to troubleshoot the problems before sending a replacement strain. This ensures that any replacements arrive alive, and/or that culturing conditions of the end user are tweaked to better grow the strain once received.