Hi Kunal, without knowing what you're measuring as a lead it's hard to give a precise answer but assuming it's something like the completion of a contact form then the answer is that ultimately you're dealing with human beings, not robots.
Ask any shop keeper and they'll tell you that sometimes they have good days, sometimes bad, but their shop doesn't move and the products they sell don't change. It's simply the random nature of human behaviour and is quite normal. In fact, I would be very suspicious of an AdWords Account where the number of conversions or leads was the same every day - that would be very unusual.
Hello Kunal P,
Why does Mc Donalds sell different amounts of hamburgers in the same restaurant every day, even if the price is the same, the Advertising is the same and the location is the same ?
The answer is : because traffic is a variable.
Different people visit your site every day, with free arbiter, free will, they may or they may not want to ask for your services. You can only adapt to trends and work within some estimates , there is no constant value for intentions or traffic.