Very few long-lasting TV shows keep the same cast all the way through. There are exceptions, but honestly if a show lasts more than four seasons, the odds are good that someone will leave, even if it’s a recurring character and not a series regular. It happens. Larry Linville didn’t want to keep playing the thankless role of Frank Burns as who can blame him. Gretchen Corbett had issues with the studio that I haven’t been able to unravel and couldn’t keep playing Beth Davenport on The Rockford Files. Famously, Shelly Long and David Caruso thought they could break into the movies, and it didn’t work out the way they’d hoped. A factor worth noting, though, is that the show sometimes includes scripts written for one character but produced with their replacement.
You can’t blame them, really. Especially when a replacement happens with little notice. There’s got to be at least one Night Court episode where they crossed off “Selma” every time it appeared and wrote in “Florence.” Though it’s hard to tell given how similar the characters were. NewsRadio doubtless had some issues with the death of Phil Hartman. You do what you have to, and if that means keeping a script in place and replacing one character with another, well, that’s going to be the least of the show’s troubles. The challenges of replacing the character go far, far beyond a few measly scripts.
It’s a little more surprising when a character has been gone nearly two years. “Love Is the Word” is a Rockford Files episode that’s clearly been written to close out Beth’s character arc, but Beth’s last episode aired on January 8, 1978, and “Love Is the Word” aired November 9, 1979. So they gave the part to Dr. Megan Dougherty, a blind psychiatrist Jim had encountered once the previous season and tried to fill with the emotional weight seeing Beth marry another man would have by telling us they’d dated a lot off camera. The acting is solid. The script is solid. The emotions don’t work.
Winchester’s Frank Burns script was his eighth episode, but you didn’t need eight episodes to recognize that it didn’t fit his character. Having Charles involved in a petty scheme to get a few hundred dollars out of the local population seems like too much work for too little reward for a man worth as much as Charles. If he can’t clear at least a grand, Charles isn’t going to go through that much effort. It’s a Frank script and obviously a Frank script, but they had Charles, so Charles it is.
All sorts of shows will probably reveal this sort of thing if you examine them. It’s likely less obvious for something like the Law & Order franchise, where to replace Lenny Briscoe you just reduce the amount of zingers. Some episodes have personal development, but a lot of them are just case-of-the-week stuff. However, with the shows that deal with personality, you’re going to be aware of the differences. It happens, and it’ll keep happening. As long as characters keep leaving shows, the scripts will keeping getting adapted for them.