There are a few dreary bits here and there after Condom and more so later on, but I'm surprised folks make such a big deal about the contrast. I tend to take the scenery as it comes. Less dramatic can mean easier going, allowing you to look up, hold a conversation with a fellow hiker or the sky, breathe differently.
If you just walk until you run out of time, then you'll have to consider how to leave the chemin and get wherever you need to go. In the very late stages, I think bus service can be spotty/non-existent, so you might be looking for a ride, taxi, hitch, etc.
If you end your walk as early as Aire sur l'Ardour, which I believe is the last place you can get an SNCF bus to leave the chemin (for Pau and onward rail connections), you cut 5 or 6 days off the trek to SJPP.
If you feel a need to reach SJPP, there's an SNCF bus from Condom to Aire sur l'Ardour. That would allow you to skip 3 or 4 days of hiking. You'd miss Lectoure and some other spots I like, but avoid the dreary (IMHO) long, flat (but shady) slog into Eauze.
Bill