I have located info on this.
Grouping is done by default and is hard coded, but you can shut it off via the database in ch_wall_handlers by changing groupable from 1 to 0 on the event you do not want grouped then clear the cache. It will not ungroup any previous entries. Only new entries will be ungrouped.
The group size is set to 3 items and the time frame for the group is 24 hours starting from midnight on a given day. Both of those are hard coded into the code.
I will be working on that for the next version of Cheetah. There is not enough time to get it into the upcoming version due out next month, so it will be the version that follows.
I will add options for turning grouping on/off, the number of items in the group, and the time frame for the grouping. These options will be added to the settings of each module that does it which is currently photos, videos, sounds and files.
But JohnK is correct, it is done the way it is for a very good reason, and that is to prevent those that upload dozens or even hundreds of photos from pushing everything else off the outline. So even tho i will add options to change it, the defaults will remain as they are.
Also, i am aware that mutipal files can be selected for uploading, and grouping could be done in that manner as well, but unfortunately even tho multiple files are selected, with the way php handles uploading, the files are uploaded one at a time, so there is currently no way to make this distinction between a single and multi file upload. But i will try and find a way around that as well.