Using ls -lt to sort a file listing by last modified time is simple and easy. If you have a large directory tree with tens of thousands of directories, using find with some massaging might be the way to go. In this example there is a directory with many directories in a tree like this:

./1
./1/1
./1/1/1
./1/1/2
./1/2
./1/2/3
./2
./2/3
./2/3/4
./2/3/5
./2/3/7
./2/3/8

we are interested in the 3rd level directory and getting a list of which ones were most recently modified

# find . -mindepth 3 -maxdepth 3 -ls | awk '$10 !~ /^20[01]/' | sed -e 's/:/ /' | sort -k8,8M -nk9,9n -nk10 -nk11 | awk '{print $12" "$8" "$9" "$10":"$11}'| column -t | tail -10

We start by finding only 3rd level directories with extended listings (there are no files at this level, so -type d is unnecessary). Then use awk to only print directories that have been modified this year (i.e. anything with a year like 200* or 201* instead of a hour:minute in column 10). Replace the time colon HH:MM so that we can sort by minute after we sort by hour. Then rearrange the columns, add back the hour:minute colon, run it through column to get nice columns, then get the last 10 results.

./586/1586/1311586  Sep  16  16:11
./980/6980/2326980  Sep  16  16:18
./616/3616/513616   Sep  16  16:20
./133/9133/2119133  Sep  16  16:21
./422/6422/2106422  Sep  16  16:24
./566/6566/2326566  Sep  16  16:46
./672/672/2310672   Sep  16  16:51
./680/680/2290680   Sep  16  17:42
./573/5573/2325573  Sep  16  17:47
./106/1106/2321106  Sep  16  17:49