Joint mobility work is necessary and should be done every morning. If you have a popping or creaking joint, double the work. If it is painful, move slower, consult with a professional and - with his consent - triple the work.
Because Every Set of Weight Training Should Reach Muscle Failure, joints are under a lot of stress during weight training. It is good to warm up before workouts, but it’s also good to do mobility work as a totally separate (earlier) session.
Stretching and joint mobility is essential to avoid the Runner’s Knee.