I use a case gague ...but I don't know about the other tool you mention.
Yes, I think a case gague is a mandatory tool. Using a case gague - I drop every finished round in ..and tip it up and drop it out. Its a quick way to check the overall length ...and to make sure the finished round will chamber properly. If they stick going in or out of the case gague ...I reject the round. When it sticks ..it might mean you need to make an adjustment to your final crimp die ...or there is a little burr on the case base or a crack in the case that you missed - that showed up as you seated the bullet - so now the case is under pressure.
But a case gague - is the final step I use ...as I box up all my rounds. It eliminates any feeding issues.