Heraldic Visitations have not been undertaken since the time of Charles II, and the type and level of proof required by the Heralds at the time varied with each Herald, Visitation and county, but all must be taken in historical context.
Whilst the original finished Visitations are at the College of Arms in London, the notes taken by the Heralds when visiting the counties became largely lost into private ownership.
No Visitation, whether the original finished article at the College of Arms, or the heavily edited versions now in print can be taken as primary source evidence when attempting to prove a family pedigree, whether for family history purposes or to claim the right to a Coat of Arms.
A Select Committee on Public Records in the United Kingdom 1800 specified eight categories of records:-
Visitation Books, Modern Pedigrees, Peers' Pedigrees, Baronets' Pedigrees, Funeral Certificates, Records of Royal Marriages, Coronations and Funerals, the Earl Marshal's Books, Books of Arms of the Nobility of the Knights of the Garter and the Bath, records of Grants of Arms.
Four more were added in the 19th century; Lists of Knights, Pedigrees of the Knights of the Bath, Scotch and Irish Registers and Partition Books. (with thanks to Thomas Woodcock, Garter)
Church birth death and marriage records were not required to be kept until 1538, although many did not start until later, and many have been lost to fire, flood, vermin, mould, wars etc.
To lodge a pedigree now at the College of Arms, it has to be backed up with primary source evidence, and will be checked by two Heralds before it is accepted.
Similarly, to claim the right to use a Coat of Arms, you have to back up your claim with primary source evidence back to a man known to the College of Arms as having a legal right to those arms, or to the person to whom the arms were granted or confirmed in their records. This is again checked by two Heralds.
If you are not concerned with English pedigrees or arms, please refer to the relevant grant issuing authority, such as the Court of the Lord Lyon in Scotland.
If only the same level of evidence and recording had been required in previous centuries, the task of drawing up a reliable and truthful pedigree would be much easier.
Historical records must always be taken in historical context, with a knowledge of the laws and politics of the period in history that you are researching.
