Stop worrying about the percentage of jobs you are closing and focus on closing more jobs you want to do. If you live off of referrals, sorry, you’re a slave to whatever walks in the door.
If you get a chance to do one job you like vs. two jobs you don’t, take the one. There’s more to this game than money. Besides, doing the job you like means you will probably do a better job which means more referrals.
If you are a high volume shop who needs to keep a lot of people fed and a lot of trucks on the street, you should pay attention to the type of jobs you are attracting. That comes from paying attention to your marketing, your salespeople, your upsells, your cross-sells, your website.