Creating Sparsebundle Disk Image - Which Partition Scheme?

Using Disk Utility, I'm creating an encrypted sparesebundle disk image on an external hard drive. In reading about the steps, people seem to differ on the correct setting for Partition Map. I found recommendations for:

1. Single Partition - GUID Partition Map

2. No Partition Map

I more or less understand the differences between Single Partition - GUID Partition Map and No Partition Map. And I've had success creating encrypted sparse bundle disk images in the past using Single Partition - GUID Partition Map.

But can anyone explain why No Partition Map exists, and why it would be preferred over Single Partition - GUID Partition Map for an encrypted sparsebundle disk image?

Thanks!