The in-tank filter socks are advanatageous in that theyhave a much greater area than the in-petcock or inline filters and are less prone ro getting overloaded and clogging. In addition, since they have gasoline swilling back and forth on a regular basis they tend to be self-cleaning. When I do my yearly tank "cleaning" in the Spring I remove the tank and slosh a quarter-gallon of gas (with a couple ounces of denatured alcohol) around vigorously and pour that gas out quickly to remove sediment and trapped water.
Even then, I consider the in-tank filters as primary and use sintered bronze in-line filters as secondary.
'73 R60/5 Toaster