They help cut through the complexities of researching blind. Depending on the state, a will may be files as the only document or there may be additional papers filed concerning the disposition of property and assets in a person's estate. The laws vary from state to state. You may find a will for one person and the estate in the spouse's name. Knowing who died last is helpful because that is where the disposition of the land and property usually takes place if things were not divided up during the person's life.
Old wills can be fascinating.
They are often written in the handwriting of the person involved and witnessed to by close neighbors or friends. There are old terms used that are not around today and sometimes these take a little bit of extra research. Depending on the laws of the state and the time period, a person may have listed all or none of their family as heirs. Some states required that everyone be listed even if they were not to receive a large share of the estate. The dollar had to be noted and given to show that the deceased meant for that person to be excluded.