Hi Pragya
CMN_JOB_ANALYZE_SP will by default analyze PPM table stats at 50%. You may increase this percentage but in our experience it's usually more beneficial to run 50% of the stats as opposed to 100% (comparing results, efforts etc.). This is why this setting is by default. If your DBA finds some specific tables need more stats to be run, they should run the stats more only for these tables. The job is here for your convenience but it doesn't allow for much customization. As Dave said above anything that goes beyond should be taken care by the DBA.
I hope this helps -Nika