In some very specific circumstances -- like you’re training for a physique competition -- spending lots of time on isolation exercises for smaller muscle groups makes sense. For the vast majority of people? They’re a time suck.
Most people don’t need to do more than eight to 10 exercises in a single strength-training session, and most of those moves should be compound exercises that target multiple muscle groups at once. Exercises like squats, lunges, push-ups, and pull-ups target larger and smaller muscle groups at the same time, making excessive isolation moves largely unnecessary.
That said, isolation exercises aren’t completely without merit. The trick is combining them with other compound exercises to maximize your workout while minimizing your time. For instance, add a biceps curl to a lunge, or a shoulder press to a squat. Mix up your foot placement during squats and lunges to target your abductors and adductors while also hitting your quads, hamstrings, and glutes. An efficient workout = a better workout in less time.