This movement may seem weird at first since most people will do lunges with feet at approximately hip width position when they are doing the movement pattern as for this movement requires your feet to be one in front of the other and in line. This movement pattern is my favourite one because it is one, challenging for most people and two, is a great way for me to notice how my clients can stay connected to their core when their stability is challenged. Not only does it challenge the integrity of your core but it also gives information on the mobility of the ankle, knee and hip of both the front and the back leg as well as how limited the person is in their thoracic spine mobility. From my perspective, the inline lunge is an awesome movement pattern.
My question for you is how do you use the lunge in your training? Do you do split squats or lunges? Do you also challenge your balance with the lunge pattern? You can use many tools like a disk, a beam, a kettlebell, you name it!