Each facility is different, each process is different. You have to establish your own baselines and tolerances for the type of environmental testing you are doing as it relates to the risk of your products.
For example, you will have much lower limits on Zone 1 and 2 areas, than zone 3 and 4 areas. I suggest you start with making a zone map for your facility and strategically samples after sanitation has been completed and it is visually clean. Then sample during production and then after production is finished prior to cleaning. If you do this enough you can start to see a baseline where you can draw limits for each area and type of test.
In my most recent position we started a brand new milk processing ESL plant back in May. I'm still determining our baseline levels for environmentals and will probably need at least a year to see where we stand.
Be patient...be strategic. So long as auditing bodies and inspectors see you are conducting regular monitoring and acting upon issues that pop up then you'll be fine.