That's kinda the whole thing with Standards; there's always exceptions to the rule.
Create an SOP for how to process 3rd party drawings. If you frequently work with certain companies, spend some additional time setting up automations to expedite the tasks where you can.
How you process 3rd party drawings likely depends on the data they've provided and the level of information you want when done.
In Civil 3D, sometimes that's simply exporting LandXML, Copy+Paste, or a simple WBLOCK. If dealing with survey data that's broken out with layer-context (meaning COGO Points are on element-specific layers for roads, top of bank, etc.) and you don't want to lose that level of detail by using LandXML, you now have to save a copy of their drawing, bring in your Styles and Settings and move their data into your layers, styles, etc.
Document the stuff that's frequently repeated, or critical to your company's needs. Develop some tools that make it easier for users to do the right thing when needed. This encourage users to be more independent, which just builds trust (in the tools provided and in them) and that makes your team capable.
