There are a LOT of branches...I frequent the LKF branch, always for lunch, and I never eat in. I usually have to wait about 10min for my kebab; I've never experienced a lengthy delay--they seem quite fast and efficient. Different preparers make the kebabs slightly differently, and I have noticed the chicken tikka tasting a bit drier than it used to--maybe they're skimping on the spicy sauce?
FYI, the biryani special is not featured at the LKF branch, but they do have the chicken kebabs on lunch special (w/free soda, $49), and the curry rice, I think.
Based on my experience I will continue to patronise the LKF branch at lunchtime, but I will think twice about eating at any of their other branches!