What is your ideal campaign length for a video game?

If you had asked me this as a high school kid, I would infinity, keep it going. Now as an adult who strives to finish games and get a sense of completion, I feel like 6-8 hours would be my preferred with optional content pushing it to 10-12, and 100% pushing it to 20 hours.

I understand that some games are expensive and you want to justify it, but as someone that plays on the backlog most of the times, my cost of entry is a lot cheaper than most people's.