I have a 5-year old Hackintosh still going strong on El Capitan. I would say a few days each year of maintenance is a minimum to keep it running smoothly and updated.

I started off with free parts from friends and bought a semi-supported motherboard. Since then I've upgraded a GTX, added ram, switched PSU, added TB drives and bluetooth. My advice is to get supported parts as far as possible.

I get a huge productivity boost when I can use it because I can plug in several huge displays and my best keyboards/ mice. It's exactly like having a Mac Pro except slightly more fragile.

I can foresee still using my Hackintosh for the next few years because it's performance hasn't degraded. I will just keep swapping parts and upgrading as needed.

Plan for it to fail during crunchtime, and make sure you keep your Macbook handy. My Macbook Pro and Hackintosh work synergistically to repair and update each other :)