When there was 4 files in source and none at destination:
a successful transfer returned 0 checks and 4 transfers.
When there was 4 files in source and the same 4 at destination:
a successful transfer returned 4 checks and 0 transfers.
When there was 1 additional file at source than at destination:
a successful transfer returned 4 checks and 1 transfers.
When there was 1 file was modified at source than at destination:
a successful transfer returned 4 checks and 1 transfers.
So I think it can be used as a proxy for number source files only when they are present at both source and destination. Any idea if there's a stat for # of source files in all scenarios?