Japt: Count overlapping substrings
Finding the number of overlapping needles in a haystack in Japt is slightly verbose, clocking in at 12 bytes, but still a fun fiddling exercise for a change.
ðV // Get all indices of needle in the input.
ä // For every consecutive pair of indices
Ï-X // check whether their distance
<Vl // is smaller than the needle length, e.g. whether they overlap.
è // Return the number of items that were true.