The Guide To Rep Ranges
The benefit of in-person coaching or the online training service is that your rep ranges will always be pre-determined for you. So you never have to worry about doing too much or too little.
If you are training in the gym and you see another lifter performing the same exercise as you but doing a very low amount of reps or a very high amount of reps there is no need to change what you are doing because rep ranges are programmed bespoke to you, according to your current progression in your training.
If your rep range is 8-10. This means that you warm up as described then at your working weight for each set you are aiming to lift it at least 8 times. If you only lift it 6 or 7 times in a set, it is too heavy, reduce the weight for the next set and aim to hit 8.
If you can lift it for 10 reps for all your working sets then you have gotten stronger and it's time to increase the weight. When you increase the weight it is common to find that you then come back down to just being able to get 8 reps. You will of course adapt to this weight over time and increase the reps. Once you hit 10 reps for your sets you can increase the weight and go from there.
Other common rep ranges are 4-6. In some cases, your programming might just call for 3 sets of 5 reps every session, and instead of the reps changing the weight is increased driving strength progress. This style of programming is also used for training and I will set your numbers for these lifts. You can ask about this or any method of training at any time.