In 1861 Richard Sims wrote the manual for the genealogist which provides some potential sources I had not considered. For example Knights Fees were well documented and there are books available online.
The preface of the book points to the challenges in 1861, which somehow feel very similar today.
Richard Sims 1861: The study of Heraldry and Genealogy, like that of many other sciences, is approached by no “royal road,” but is beset with difficulties sufficiently great to deter all but the most enthusiastic, from the pursuit of an employment to all appearances so dry and unprofitable.
Nevertheless, the number of students in this useful department of history is daily on the increase; hundreds of persons derive pleasure from this mode of passing their leisure hours, whilst there are very many, who laboring under some real or fancied wrong toil incessantly for the discovery of facts wherewith to connect the broken chain of a descent, and establish a claim to wealth or title, long since apparently within their grasp.
The materials existing for the successful prosecution of such pursuits are numerous and scattered : some jealously guarded and rendered nearly unapproachable by the heavy fees demanded for their production, whilst others, and we rejoice to say by far the greater portion, are readily accessible to every inquirer, who knows where and how to seek for them.
Manual for the genealogist 1861 Great Britain