It’s important to modify, adjust, or even substitute exercises to fit one’s ability, injuries, focus, and goals. Sometimes, It’s even worth modifying a movement in order to simply get the best out of an exercise. For example, if you can do a full set of regular pushups, but you can do even more when doing knee pushups, it’s worth doing some regular pushups then continuing on to do as many as you can with your knees on the ground. This way, you can get more reps in, and achieve more than with doing less of the complete movement.
In my case, I have had a week of adjusting and substituting my exercises. I recently took a week break (my first real break in over a year) due to a shoulder injury. Recovering from a shoulder injury can take a lot longer than a week, taking away your ability to do most upper body workouts. But personally, I find it difficult to stay away from the gym and upper body exercising for too long. So as my shoulder recovers, I’ve been adjusting my barbell grips (from my goal preferred wide to narrow) and substituting some exercises (either changing to low weight and high reps or using a barbell instead of dumbells) to keep the movement and pressure on the shoulder to the absolute minimum. This enables me to continue working out while recovering steadily from my injury.
Still it must be done with caution to absolutely ensure the injury isn’t worsened and continues to recover. I find that testing an exercise and the weight before jumping into a full set allows you to asses the injury comfort/discomfort and danger levels.