Hi Khadiza,
I have been writing here for two and a half years now and I often spend hours on each one. I only post about once a week. I think readers get fed up if I post too often, and I unsubscribe from anyone that posts daily. I think a good read time is around five minutes, but in truth, each story is as long as it needs to be. I think anything over 7 minutes probably needs a good edit. But that is just my opinion. The most helpful advice I can give is that when you have written something, leave it alone for a day or two, then re-read it with fresh eyes. And only publish something when you feel it is the absolute best you can do.
I did (in the early days) sometimes post very short things that only took 30 minutes to write. But I've gone back and deleted most of them!!
Someone once told me that the stories we don't want to share are the ones we should be writing. When I plucked up the courage to do that, it got boosted. So, I think that was good advice. Wishing you well on your Medium journey. A🙏.