Originally Posted by lj01
I don't know if this has been addressed, but I don't see it in the reviews or anything so thought I would ask...
Season 8 is of course famous for the absence of Shirley, among other characters, however...
Per Penny's book, they had originally decided to end the show after S6. However, Cindy Williams changed her mind at the last minute and TPTB used that to leverage most of the cast back.
Most of S7 was shot in a hurry to accommodation Cindy William's visible pregnancy. If you look in the later eps, you can see that she's showing. In the two S8 episodes she was in, she looked like she was ready to pop.
Penny Marshall had lost interest in the series by S7 and did what was only contractually required of her. Michael McKean was shooting/shopping "This is Spinal Tap" and making/promoting "Young Doctor's in Love". He's said in multiple interviews that the show had been very lenient with him regarding his other projects.
Betty Garrett had already committed to a play on Broadway when she was told that the show was going to run another year, hence Edna's "divorcing" Frank.