Professional bodybuilders love their equipment. They constantly wear weightlifting belts, gloves, and straps. The beginners imitate. Monkey see, monkey do. As a result, it’s not uncommon to see unaware individuals using straps for every exercise.
Straps are a valuable training equipment that gives you an opportunity to increase your workload when your hands are the limiting factor. The manual says, however, that excessive reliance on straps produces weak grips.
A common way to limit the negative effect of straps on your grip is to remove them from your warm-up sets. That way your forearms will continue to get stronger as your warm-up sets get heavier. If you were to deadlift, for example, you could skip the straps until the last set or two of your routine.
As far as supplemental exercises such as rack pulls are concerned, you can do something similar – straps off for the warm-up sets and straps on for all working sets.
What about pull-ups?
I don’t think you need straps for pull-ups at all unless you are injured or working on your technique (back activation). Even weighted pull-ups do not require that much grip strength, to be honest. However, if you are suffering from elbow tendonitis, straps may be a legitimate way to reduce the pressure on the hurting structures.
Straps could also be useful when you are learning how to activate your lats.
Straps allow the arms to relax since the forearm muscles are not as tense. As a consequence, it becomes easier to treat your arms as just hooks when learning how to activate your lats during pull-ups.