A more simplistic solution might be to use the CSS column property, that way you can control the amount of columns in your breakpoints (also gutters).
Additionally it seems all together a good idea to me that if you can achieve the same effect without a bunch of explicit containers then you should. Obviously there are things to consider with flow that might make that decision for you. Hope this helps add to the above answer a bit.
.container {
-webkit-column-count: 3; /* Chrome, Safari, Opera */
-moz-column-count: 3; /* Firefox */
column-count: 3;
-webkit-column-gap: .5rem; /* Chrome, Safari, Opera */
-moz-column-gap: .5rem; /* Firefox */
column-gap: .5rem;
}
.note {
width: calc(100% / 1);
}<div class="container">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_ugarkovic_saturn.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_iapetus_sidebyside.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_mimas.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_ugarkovic_saturn.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_mimas.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_iapetus_sidebyside.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_iapetus_sidebyside.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_ugarkovic_saturn.jpg.CROP.original-original.jpg">
<img class="note" src="http://www.slate.com/content/dam/slate/blogs/bad_astronomy/2014/06/Ten%20Years%20at%20Saturn/cassini_mimas.jpg.CROP.original-original.jpg">
</div>