It's okay to walk away.
If you've been grinding on something for months with no real progress — stop. If you've been "perfecting" the same script for years — stop. If you keep finding reasons not to open the final draft — stop.
Don't power through out of stubbornness. That project is stealing time from the script that actually represents you and your talent.
Take stock. Ask yourself: Why am I writing this? Is it worth my time?
If the answer is no, ask the harder question: What story is?
Your best work isn't the one you suffered through. It's the one you couldn't wait to get back to. Find that one.