Gaiwan brewing always ending up bitter

If your pour is really slow it maybe that you are not inclining the lid enough when pouring. It doesn’t have to be much but if your lid remains flat and flush the pour tends to be very slow.

As others have said the three variables I tend to experiment with to reduce bitterness are amount of leaf, steep time and temperature.

I find I have to experiment the most with rolled oolongs as I find there is no consistency with steep times with them. I had three Teas from one vendor and the initial steep times varied with each one. One was 30s first steep than 20 for the second with future increases of 2-5 s. Another was 5s first steep and a 2s 2nd steep. This particular vendor suggested longer first steeps to awaken the leaves.