Workout intensity is more important then workout duration.
Workout duration is heavily linked to increased metabolic effects. That doesn’t mean longer workouts give you better results. In most cases it’s likely if your workouts are lasting longer, you are able to do so, due to your overall workout intensity not being as strong, giving you the ability to last longer.
Lets take endurance sports such as marathons and triathlons, its not about who can last the longest it’s about who can finish the fastest, my point, it’s about who has the most power endurance, with this reality in mind, you should be looking to gradually progress your workouts by continually trying to perform your workouts more effective, not just longer for the sake of going longer.
When you add sets, reps to your workouts, they add time and take longer, which is fine. However, there comes a point, when you have to stop, you can’t just keep adding on. You can make good gains in progress by making your training/ workouts more intense/challenging/harder by trying to complete the same workout in less time then your previous session. In doing so this boosts your workout intensity. Another way to make your workouts more challenging is get more out of your session by way of >sets, reps or weight lifted in any given workout, In the same time frame then you did in your previous workout, which also boosts intensity.
Don’t get me wrong, there is nothing wrong with increasing reps and taking your workouts a little longer then previous sessions, but simply relying on that method to progress, is unrealistic.
There is only so much time in the day to workout, train. Remember the goal is to get as much quality work done in that amount of time. This should maximize your results.
Happy Training. Rich