I think we all have ancestors who we see as on the back burner. Brickwalls whom we keep in mind and occasionally revisit them to see if anything new crops up. As we know it is not easy and often we are no more knowledgeable than before, but we still keep them on the backburner. One day we may strike lucky. But if you focus too much on a certain brickwall it can become overwhelming so best to leave that line for a while.
For instance, using an example, my ancestor James Gater, a maltster of Burford, Oxfordshire. Born c1680, died 1737 in Burford. No instances of the surname seem to be in Burford before his 1711 marriage to Hannah Bayliss, and he did not leave a will. I have a beady eye on the James Gater born in 1679 in Lambourn, Berkshire, about 15 miles south of Burford, son of Wm and Eliz. But it is tough trying to establish if they are the same person, or even if they are not. James's son James Gater born 1714 took on a Thomas Wentworth as a baker apprentice in 1745 in Burford and there seems to be several Wentworth families in the Lambourn area and Bedwyn Wilts. James Gater Snr seemed to have work connections to Gt Rissington in Gloucestershire.
And another example is my ancestor John Lucking (c1722-1786) of Foulness, Essex, his age at death was said to be 64 in 1786. I found a website about 20 years ago (long taken down now but seemed legit) which said he was the 1722 born son of Isaiah Lucking and Hannah who moved from nearby Shoebury to Foulness in the late 1720s. But I also found a John Lucking born 1725 in Shoebury to John and Mary Lucking (seems John Snr was a Shoebury parish clerk later on). A John Lucking was buried in Shoebury in 1727, no info as to whether infant or not but not John the clerk as him and Mary had children up to about 1740.
My John (c1722-1786) wed Eliz Otley in 1752 in Foulness and did not have any known children called Isaiah. But it is likely the John born 1722 and John born 1725 were first cousins. But it seems through witnesses to marriages, my John (c1722-1876) had a sister Mary (also known as Eliz) who wed Tho Harper in 1744 in North Shoebury. A Mary Lucking was born 1723 in Shoebury to John and Mary Lucking. Isaiah never seemed to have any known children called Eliz or Mary in the 1720s. But had a Jane and Joseph, as did John Lucking and Mary. Isaiah Lucking's family has been traced back quite a long way to vicars of Bucks, Leicestershire and Yorkshire.
Above are just 2 examples of brickwalls that I occasionally revisit and try to chip away at.