Hi All
@Borate....I think the set up is slightly different as I presume Andy is adding his images to a single track. Your test project did give varying results but no idea why.
@[deleted]
If you are dragging a single image clips to an empty timeline the first one should automatically go at the start of the track with no gap. This is irrespective of where you drop it or the position of the cursor. You can, however then pull it to the right and release it where it will re-position leaving a gap. Can't say why you are seeing a 6 second gap. When you drag the image onto the track and BEFORE you drop (release) it do you see a grey zone at the start of the track? This should reflect the eventual place and length of the image you are about to release.

Note that it also tells you where the drop position is........(First image is 0:00:00.000)
For my test I started with an empty timeline and cache and used Ctrl+A to drag all the images from the destination folder to the image bin and then did Ctrl+A again to select all the images in the bin and dragged them en-masse to the track. As mentioned all had the same (default) image duration and ended up in the bin order. (See previous images).
If you are still having a problem as an alternative, use Ctrl +A to select all images in the bin., (they highlight in blue) and then right click and select Place on Sequence at Start. There should not be any gap!
If you want to do each image individually just to be certain what is happening, select each one and then for the first image choose to Place on Sequence at the Start, and for all the rest Place on Sequence at the End they will then go on the track in the order you do it.
Also let us know what the duration is of each image that you have in the bin. (Hover the mouse over each) If you had an empty VP and cache when you altered the default still image value in Options/Media to 5.96 they should all show this value (even extra images you may add later) and also have this duration on the timeline. If they haven't there is something awry.
Nat