Great feedback, @Richard!
Quoting text is an essential feature and we are going to improve on this interaction in the future. It is something I use often and it isn't as intuitive or smooth as I would like it to be.
There is however another feature that you can already use and it will help you to quote multiple times. You can minimize and maximize what we call "postbar" whether you are replying or just posting. This will show you all of the posts in the conversation to use as a reference or to quote something.
Just use the arrow above to minimize this post bar and see all of the posts. You can then copy the text, maximize this post bar again and paste it. Here is a screenshot: