I was chatting with a Trader Joe's cashier Sunday. It turns out they change jobs every hour. That was a surprise to me; when I long ago worked in a grocery store, I was assigned to one position for 8 hours for every shift. Why does Trader Joe's do it? To keep things interesting: "She tells Money that the change in jobs during shifts helps to keep things interesting for employees. 'It's perfect because it breaks down your shift. You don't get tired doing one repetitive thing,' she told them." https://www.mashed.com/175743/workers-reveal-what-its-really...
If Trader Joe's can do it hour by hour, I think tech companies can do it at least every year or so.
I'm hiring right now and one of the major draws for the good people I'm talking to is the chance to do something interesting. If that's why their coming, it's unsurprising that I'll have to keep giving them that over time. For us, and for most places I've worked, I think that's doable.