You should be looking at these metrics all the time so you can assess whether you're slipping in any one area ... because you don't want to suffer a blip in your funnel. If your funnel develops a clog or hole somewhere along the way -- and it will, it's only natural -- you need to be able to identify it and fix it to keep your sales and marketing machine efficient. And if you are working with multiple different types of leads, these metrics should be considered for each segment of lead, too, so you know if some segments are more valuable to your business than others (or, even better, if some segments have more potential than you once realized)!
In brief, we are inclined to go along with someone’s suggestion if we think that person is a credible expert (authority), if we regard him or her as a trusted friend (liking), if we feel we owe them one (reciprocity), or if doing so will be consistent with our beliefs or prior commitments (consistency). We are also inclined to make choices that we think are popular (consensus [social proof]), and that will net us a scarce commodity (scarcity).