Let's say you asked for offers from 3 companies to get a service, or you filled out a form to make a purchase about a service/product/solution from 3 different websites...
The first company got back to you after 2 hours.
The second company returned to you after 8 hours
The third company returned to you 2 days later
52% of people were buying products/services from that company, even if the company that gave the cheapest price did not return to them within the first 2 hours.
That's why if you can't get back to leads on the weekend, it makes more sense to cut your marketing budget on weekends. Because the person who filled out the form on Saturday most likely either met his needs until Monday or forgot how and where he filled the form :)