The installation of the 12.2.0 upgrade filesystem on a 64-bit Linux server should be done before the upgrade window. Immediately after the installation of 12.2.0 is completed, all middle tier ETCC patches should be applied to the newly installed 12.2.0 Oracle Homes. The DB ETCC patches require an outage to complete, and should be done during the outage window as there are many 12.2 DB patches required that are not required for 11i. Are you also doing a DB upgrade during this window?
If you patch bsu for WebLogic patching, the DBA should be able to apply all middle Tier ETCC patches in less than an hour, maybe even 30 minutes.
bsu patching is slow
Patch 27238412 SMART UPDATE TOOL ENHANCEMENT V3
I just did this last weekend, took 30 hours for appTier only upgrade, DB was already 22.214.171.124.
You can refer to get inputs to minimize the upgrade downtime.
Hope this helps!
Thank y'all for your input