6 days on Camino Frances - favourites or recommendations?

Re-starting where you finished last time makes sense. Lots of people do the Camino in sections, in consecutive years. And you can reuse your credential.
Cold and some rain will be expected in late October, you can't avoid that, but nothing "extreme". I'd say it is a nice time for walking the Camino.
Late October is much less crowded, too, so you can try the Sarria-SdeC quite comfortably.

I've walked the Camino in short stages over 2 years ( and I walk slowly trying not to do more than 20km a day, max)...

5 days Saint Jean Pied de Port to Puente la Reina
5 days Puente la Peina to Navarrete
12 days Navarrete to Carrion de los Condes
8 days Astorga to Sarria
6 days Sarria to Santiago de Compostela

If you don't want to walk the last 100k or so, and frankly I wouldn't really be that bothered to walk it again, but I loved the walk from SJPdP, and on to Logrono. Not so keen on the route to Burgos from there, but after Burgos to Carrion de los Condes was also enjoyable.

And from Astorga to Sarria, that's also a really nice walk, with the exception of Ponferrada to Villafranca (but it's worth taking the alternative route from Pieros to Villafranca).

So that doesn't really help you much, but I have six days next April to walk - I considered walking somewhere in Navarra again, but opted for a few days on the Portuguese instead.

With six days, you could also walk the entire Ingles from Ferrol, and get a compostela at the end.