Re: Harsh/burnt taste
You could try fewer holes as well. 1 in the center and 6 to 8 evenly spaced between the center and out side around the bowl. I was given this tip and it worked for me with Nakhla.
Now I use a Med Egyptian bowl with a metal screen and 1 coal with wind cover and always get at least 30 to 45 min sessions. Could be a little more than that if I light another coal, but I am usually finished smoking by then anyway.
At my age being cynical and sarcastic is just making small talk.