In each of the above cases, the fictional world would continue past this half-decade point, with varying levels of success. With great longevity comes great responsibility, especially in the world of cult fiction. Die-hard fans will cry bloody murder if a beloved character is slain, and yet without that sense that the stakes are getting higher and that all bets are off, your audience winds up crying tears of boredom instead of grief.
If you are finishing your series after 5 years/seasons, you need to convey a sense of absolute finality. Even if you are going to attempt a spinoff series. Or a couple of lame TV movies. Or after your ‘final’ episode you then air the end to the previous season because the network execs wouldn’t stop screwing around with your show. (Although Sleeping in Light packs more of an emotional wallop anyway – so that worked out ok!)
If you’re planning on carrying on Post-5, then you better have something pretty spectacular up your sleeve for your End of Year Arc. Which invariably means death. And not a red-shirt death either. You need a meaningful sacrifice, someone your audience loves, someone whose loss will dramatically alter the relationship dynamics between your other characters. You need to convey a sense that despite your show continuing, everything has changed. That it won’t just be more of the same.
You also need to be accept that however you plan things, there will always be those who will reckon you should have thrown in the towel then and there. Season 6 of BtVS is widely regarded as where it started to go off the rails. Harry Potter always had its detractors, and many of them honed in on the rather excruciating Ron/Lavender/Hermione love triangle in Half-blood Prince. Crusade only got a single series before being unceremoniously cancelled.
Nothing lasts forever. Sometimes things need to change. More often, things need to end.
All of which is a massively self-important analogy to the fact that after 5 years as an administrator at Science Learning Centre London I’m leaving to start a new job and a new life in Oxford.
At the tender age of 31, 5 years represents half my working life since graduating from UEA in September 2003. I’ve had some great experiences at SLCL, made some great friends, and learned a huge amount, but it’s time to move on.