In gardening, "thinning" is critical to raising healthy plants. It works this way:
1) Plant more seeds than necessary.
2) Once the seeds sprout, pull out the weakest and most crowded seedlings.
Because you can't know what percent of your seeds will germinate, you plant extras--and thin them later if too many sprout. The remaining sprouts have maximum exposure to nutrients and maximum space to grow--perfect conditions for them to thrive.
In writing, your ideas are like seeds: plant as many as you can. You never know which ones will germinate. But once those ideas germinate and begin to grow, they'll start to compete for your resources: your time and attention.
Of course our time and attention are finite, and they can be applied to only so many creative projects. Which is why from time to time you'll need to do your own thinning and choose a portion of your ideas to receive the bulk of your time and attention. Yank the rest out of your life--or at the least, set them aside until later--or they'll drag down the overall quality of your writing.
I thin my writing ideas at various stages of my creative process. Some ideas never make it past the drawing board. Some seemingly promising ideas just don't go anywhere and need to be killed off. Some ideas have gigantic potential, but because I can only focus on 2-3 projects at any one time, I'll occasionally need to set aside certain ideas until later. And long-time QWT readers will remember my 120% Rule, where I cull the weakest 20% of my posts even after I've finished them in order to improve the overall quality of what I put in front of readers.
Finally, don't have pity on your weakest and worst ideas. Yank them.