Yes. Always! I never choose to play without if there's an option to have it. If it were possible I'd love a list of all possible routes in games as well if you can't get all the LI as a harem.
Walkthroughs are a must for me. A well made walkthrough mod is best, since it minimizes chance of spoilers, but pdf walkthroughs are sometimes better if the walkthrough mod is erring on the side of "not making it clear the future consequences".
walkthrough. I don't walk to play a game of "guess what the author is thinking". - with rare exceptions for games with well enough designed choices such that its clear what direction you're going
Walkthrough for sure. My time playing is limited and I don't want to restart a scene or gameplay a bunch of times because I forgot to pick up a fork in chapter 1 which unlocks the path for the girl I was interested in. I mean if the dev basically has a yes or no to go after a character then a walkthrough really isn't needed.