Wiktionary
adv. (context idiomatic English) At some unspecified or unknown time; eventually or once; at some point.
Usage examples of "somewhere along the line".
He intended to appropriate the stone for himself somewhere along the line and restore it to the authorities in return for money and immunity from prosecution.
With provision for transferring the number to the proper chicken, if the egg hatched somewhere along the line.
He had a vague recollection that his own denomination, the Disciples of Christ, had split off from the mainstream of Calvinism somewhere along the line, and thought it might be interesting to see the service.
I called for another dagger and one was passed to me from somewhere along the line.
Peter had no idea whether anything would ever come of it, but clearly Marie had captured Johan's attention somewhere along the line.
But somewhere along the line perhaps even in the dark back closet of the house in Connecticut where the two boys had begun their growing up something had happened to the monkey.
My guess is that somewhere along the line you were taught to associate smarts with having an edge.