Question 1: “Do you recommend doing deadlifts on leg days or back days? Also can you do stiff leg deadlifts the day after you do regular deadlifts?” – Nicolas Ortiz
To answer your question as to when to incorporate deadlifts into your workouts, you can do both; on a leg day or back day. It really is your choice. It makes sense because deadlifts develop muscles across the entire posterior chain; the glutes, hamstrings, spinal erectors, lats and traps. I primarily follow an upper / lower split routine, which means alternating between workouts that focus on either the upper or lower body only, so I don’t really have a “back” day. So I do deadlifts during my lower body workouts. If you’re following a bodybuilding routine and want to incorporate your deadlifts on your leg or back day, go for it. Just be careful not to schedule deadlifts after squats.
Stiff leg deadlifts are a different story. I would reserve them for your leg day. They are more of a supplemental or accessory lift to help increase your deadlift. But before you go and start crushing these for lots and lots of reps, a word of caution. The pictures you normally see depicting the stiff leg deadlift, where the lifter’s back is rounding over and the barbell is several inches in front of their legs, are kind of misleading. Yes, you would want to follow this technique if your goal is to have your spine snap and shoot out your back and smash against the wall. But if you’re trying to develop your hamstrings and glutes or bring up your deadlift, and do so in a safe manner, a Romanian Deadlift (RDL) is a much better option. RDL’s teach the hip hinge—a fundamental movement in the gym and in life—and can be done in a much more controlled fashion.