My YouTube channel is https://www.youtube.com/channel/UCvB0rnW5_Aq0SjMT4PKQOYg
You can make new characters from the unlocked classes whenever you want and swap them in; they all count as being in the same party.
One thing that could speed up retirement is if you have multiple characters and in each scenario, pick whichever one would advance their retirement goal the most playing it.
Yes exactly this,, I play solo 99% of the time using mostly 2 characters at a time and sometimes very rarely 3. I created my starting party using all the 6 base characters and just swap out as needed depending on whether the scenario I will be playing is relevant to a specific lifegoal. I played Tink and Crag for a long while then pulled in the MT when I noticed that I could probably retire him soon with the scenarios I had available to me. The crag retired soon after and so I have been playing with Sun and Cthulhu face icons. My Tink is now being recalled from the Sleeping Lion as I just unlocked a scenario that will further hos life goal.
Create a full of the 6 starting character and rotate depending on lifegoal requrements and scenario relevance to said lifegoals.