In general, we do not go back to the same level for each branch of the tree and each family. One can easily be stuck in 1815 for one family, while for another it goes back to 1650. For the Professional Family Tree Research, Hire a Researcher, Professional Research this is important now. In case of the Professional Research you need to give the service provider all the information that you know and come up with the solutions that they come up with. The whole process is quite important and you need to be specific for the same now.
How long does it take to do genealogy?