My suggestion is:
The track numbering assistant should offer an already existing track number in the first file as starting value.
Naturally, the starting value could be overwritten if it does not fit.
The workflow behind it:
when collection podcasts the list of files grows on a regular basis but one never quite knows when it would end.
So you get one file after the other, sometimes more than one file and I like to sort them into the already existing order with an ascending track number.
This usually means that I have to memorize the track number of the last old file, select the new files, open the track number assistant, enter the memorized number and then let the track numbering assistant do what it is supposed to do.
It would ease my frequent tasks if I could select the last file plus the new ones, open the track numbering assistant and get offered the track number from the first selected file. Like that I would not have to memorize it and type it in.
So the basic idea is: use the track number of the first selected file as starting value for the track numbering assistant.
If that number is empty, the starting value would be 1.