I've got a lot of games on my "to play" list, which are sequels. When I'm deciding whether or not to do a walkthrough for a sequel game, I have three main criteria.
1. Do I like the game? Do I like the original game?
2. Was the walkthrough for the original game popular? There are times when I really like a game, and I want to play the sequel, but nobody wants to see me play it. If a walkthrough tops 1,000 views per video, then I'd say it qualifies as popular!
Sometimes, there are weird situations like Pokémon Yellow, which is unpopular in general, but the small group of people who like it (about 100) really like it a lot. And so I'm motivated to keep going with it, unlike the new Fire Emblem game walkthrough, whose popularity doesn't seem to have topped "vague dislike"
3. Did the original game earn back its investment? That is, did I make more playing the game than buying the game? Definitely not the case with Fire Emblem Fates Conquest. Kind of the case with Aviary Attorney, which cost me $12.74 and made about $15. One hundred percent the case with Immortal Love, where the walkthrough made about double the game's price.