This is similar to the topic I raised " Option to have only the latest episode". I suggest that it be seriously considered as, like @jbohn I find this troublesome.
I have a far-from-perfect workaround that may be of help, @jbohn. In my case the podcast is an hourly news bulletin, which I normally listen to once a day at a specific time (ie when I take the dog out at noon!). Using “Episode Filter” I have only the episode with that time in the title downloaded. Works fine except if fills up “New Episodes” with the non-downloaded ones - and on the days I take the dog earlier or later!