^ Eh, no. The blanks aren't officially intentional. The routes are originally in 3 different pictures, and the image editor tried to make the start of 08.15.-2 of all 3 pictures stays in the same vertical line and tried to make all the events in 08.15.00 of all 3 pictures parallel with each other (though sort of unsuccessful on that) so he/she cropped and repositioned different parts of the manga and LN routes, thus the white blanks in between pictures. The editor did imply that this might not be the final version.
Edit: somebody else already made some text-only versions of those timelines that is very chronological and more detailed than those images:
link. If you have something to add, tell the person
here
I have to wonder where Lost Time Memory goes. The anime just doesn't really help to identify that.