Ive never trolled herring or cutplug or strip, but for anchovies I dont even look at my speed, Im only concerned with how my roll looks in the water. I often rig up an extra rod with a teaser/chovie and just watch it beside the boat to give me a rough idea what my 2 other rods rolls are looking like without having to pull them up.
Ive found I have the best luck trolling with the tide in most cases, so i try to set up to do that as much as possible, but whenever i switch directions, i always pull one line to check my roll and adjust my speed until its just right.
Good luck!
Yak