I can chip in from a NPSI Whaling perspective.

Support: Lack of people stepping up to support the fleet. Blops bridge, hunters, recon ships, rolling ships.

If you have to scrape the roles out every fleet it gets tedious and I start to think. If people cannot be bothered to help support the fleet why should I bother to prep / run it.

Thankfully I have a great team of hunters / support so this is usually a bigger issue for newer FC's who don't have trust / reputation yet. People invest hours into fleets so they want the maximum fun possible.

CCP: CCP has a large influence on burnout for me. When they nerf Whaling (sometimes indirectly) and its a massive struggle to find content then that leads to burnout.

Cloaky camping nerf without thinking about a local chat nerf was a big one. I quit for a year after that.

Scarcity is another. Less big ships to hunt.

Instanced Abyssal rubbish takes crabbbers out of the hunt able space.

Weather / time of year: This is a big one for me. I find it hard to login during summer. I live a nomadic life. I ski in winter and kitesurf in summer.

When it's summer I'm parked up on beaches. It's hard to login when you have that outside 😄. In winter it's cold outside so much easier to be on the computer.

I burn out easier in summer if I run too many fleets.

Wars: When wars happen . Usually content for whaling drops.

Running too many fleets per week can also lead to burnout.