I agree. Only God is perfect. Human beings make mistakes, and reloading manuals are written by human beings. So you need a cross check. A good rule of thumb is to check three sources and use the lowest starting load among the bunch.
The Hodgdon reloading site
has a lot of data. Unfortunately they are having some sort of contractual problem with Olin over the Winchester brand in that testing that is supposed to be updated by Olin periodically for liability purposes has not been done, so Hodgdon has started dropping Winchester load data where the last test date isn't current enough. For the Hodgdon and IMR brands they are current, though.
You can also buy and use QuickLOAD as another opinion. Again, like any other load data source, it's not to be trusted by itself unless already verified the behavior of the component combination in your weapon. A chronograph for feedback is a necessity with it, IMHO.
In most instances you can also call the bullet maker and ask for a recommendation.