This may belong in the Essex group but this is more a general question about being thorough as opposed to a request for help.
My ancestor was John Newman who wed Mary Daniels in Rochford, Essex in September 1780, he was a bachelor, witnesses John Topsfield and John Wade (parish clerk), both left their mark. I am 99.8% sure he is the same John Newman baptised in early February 1760 in Belchamp St Paul, in north Essex, son of Samuel and Hannah Newman. John of Rochford named his eldest daughter Hannah and he later had a son called Samuel Newman who died in 1796 as a infant. John's father Samuel was from Clare, Suffolk and flitted between Clare and Belchamp St Paul. His wife Hannah died in 1763 and he remarried. His other children seemed to remain in Clare, Suffolk except John.
John Newman of Rochford died in 1811, no age given at burial, and no will left, but he was subject to a settlement examination in April 1782, where he said when he was about 17 he was apprenticed to Joseph Turner of Southminster, Essex, a shoemaker, for 7 years and they agreed to part after 4 years (so must have been when John turned 21), and that he is now married to Mary and they have no children as yet. A settlement cert for John was issued from Southminster to Rochford in May 1782. John and Mary's first child was born later that year. No record of the apprenticeship to Joseph Turner seems to survive in the list of indentures so I assume it was a pauper one but he was 17 when apprenticed, and I read the maximum age was 14 for pauper apprentices.
Joseph Turner was the stepson of William Newman who wed Joseph's mother Elizabeth in 1768, she was a victualler. This means Joseph took on his step cousin as an apprentice as it seems John Newman was William Newman's nephew. William Newman was from Clare, Suffolk, originally and had 2 children, a daughter Sarah in 1753 and a son William in 1755. No other baptisms of children for him can be found in either Clare or Southminster. In Nov 1757 William moved from Clare to Southminster as his brother Thomas indemnified Clare from expenses for William's settlement in Southminster. By 1768 William was a husbandman when he wed Eliz Turner.
Thomas Newman of Burnham On Crouch, Essex, just a few miles north of Rochford, left a will in February 1783, it was proved 5 years later in January 1788. In his will he mentions various relatives including his brother William Newman of Southminster, and several nephews but it seems he did not mention every single nephew according to further research. He does mention "My nephew John Newman of Rochford, son of my brother Samuel of Clare, Suffolk" leaving him £20. Also he mentions "My nephew William Newman of Rochford, son of my brother William Newman of Southminster".
I may be being over cautious here but I have scoured Rochford rate books, settlement certs/examinations, baptism, marriage and burial records 1775-1811 on Family Search for Rochford Essex, and there appears to be no other John Newman living in Rochford at the same time as my John Newman.