for me, a good logo is one that meets the expectations of the client, it is also quite simple, recognizable and memorable, but the last sentence and the decision is, of course, to clienting because he will use logos
and it does not matter whether the logo was done in 15 minutes or 2 days, but must comply with the expectations
I have done 3 min logos mostly for those who like text based branding. But the time is dependent on how intuned the designer is with all the tools and extensions available. There are many ways to get the same results some are better than others. Most get comfortable with the few palettes and never take the time to learn the others. Some of us use keystrokes instead of menu or palettes which also reduces time.
Not only knowledge of Adobe but also the new trends in branding or a specific niche market.
So many factors are based on time upon creation. Look at some professions like a lawyer.... GOOD EXAMPLE... When you call your lawyer it will cost you money... Usually big money lol... no matter if the conversation was 2 mins or 2 seconds your paying a flat rate per hour.. What your paying for is the expertise and experience of this service.