If there is one I've learned in the past months is that 9 times out of 10, improving what you already have is better than starting afresh or "going back to the drawing board". Yesterday, I read an article by Nathan Barry that drives this point home:
That’s something I’ve heard a lot: if something isn’t good enough, it’s time to redo it. Sometimes that’s necessary, but more often you should use the foundation you already have to get closer to perfect.
https://nathanbarry.com/scratch/
There are situations where starting from scratch is the best course of action. However, most times if you already have something, you should focus on improving that thing rather than looking elsewhere because when you start from scratch not only will it take longer but you'll end up having to face obstacles related to the new direction. No way is a freeway and don't get fooled because you think the grass is greener on the other side. Whether it is in relationships or projects, improving what you already have and capitalizing on marginal gains (1% better every day) makes what you already have stronger and better than what you could hypothetically have. At the end of the day, the option to start afresh is another journey with a lot more unknowns than what you already have.
Another thing to be wary of when deciding between improving what you already have and starting from scratch is sunk cost fallacy. The line of thinking in which you spend more time, effort, or money because you've already invested a lot. The amount you've invested into something shouldn't be the sole driver of whether you should keep doing it or not. Sometimes the situation is beyond repair or improvement and in those cases, it is better to cut your losses and move on. This is especially the best course of action if you keep moving forward hoping on some sort of good fortune for things to get better so that you can recoup your investment. Another variant of this is repeating the same actions that caused your losses hoping that they'll help you avert your losses somehow, needless to say, this is madness.
All in all, when given the choice of improving what you already have or starting from scratch you should err on the side of improving what you already have. If you're way past the point where any improvement would help make the situation better (except through some lucky event) then you should cut your losses and move on. Whenever you get yourself in those situations ask yourself these questions: Forgetting the cost and investments you've made so far, would you keep moving forward with the current situation? If you weren't already involved, would you still invest in this?