You need to follow the supported update order as described in the Admin Guide. See Administration Basics — Enterprise Administration Guide.
As show in the release notes, .15 is an OOC patch which must be installed over .14. See
11.0.15 Out of cycle update, March 8, 2016 — Acrobat and Adobe Reader Release Notes
Basically, planned updates are cumulative, so all your machines should just install the latest planned update and the last patch.
HTH,
Ben