I looked into long running operations for FormRecognizer dotnet SDK.In addition to this I want to know the estimated time that is taken for document analysis
It would be helpful if can find any documentation that talks about time estimation for Document Intelligence
Based on my various tests of Azure Document Intelligence (formerly Azure Form Recognizer), the processing of a single page document takes generally less than 5 secondes (I would say between 1 and 3 seconds). You can make your own tests easily by setting a free Document Intelligence resource on Azure, and test directly on the Document Intelligence Studio: https://documentintelligence.ai.azure.com/studio
If you use the dotnet SDK (and python SDK - same story!), don't forget to set the "long running operations" parameters as you want. Because the default value can be inappropriate (it used to be 30 seconds in version 1.0.0b1 of the python SDK for example! came back to 5 sec in 1.0.0b2)