"To waste the effort" means to use time, energy, or resources on something that doesn't produce any valuable results or outcomes.
Sentences with «to waste the effort»
Just saving one month of wasted effort in a job search can easily translate to savings of thousands of dollars. (maryelizabethbradford.com)
Also, don't waste your effort on writing something that won't get you into your chosen college. (studentsassignmenthelp.com)
Their problems were that they were so concerned with acting «holy» that they didn't waste effort on showing compassion and love. (religion.blogs.cnn.com)