your question is a bit odd and the answer (as long/short as you make it, depending on your play style and goals, which we can't possibly know) a bit obvious but i'll try to be helpful none the less.

I decided to not look up any videos or info in the beginning and got very frustrated and ultimately done in by a VERY tough seed (map). If I didn't start another map I'd still be trying to find the second boss. I started a new map and watched a video about sailing and I then progressed just fine. I'm waiting for mistlands to actually defeat the 5th boss but I got to that point at around 120 hours. I play slow and enjoy.
I'm up to about 520 hours now because I do a lot of building and I also have a modded survival character as well as a modded building character, all with their own maps.
"Lack of content": I'll admit there could be more but the more creative one is, the more content they will find.