Are Isolation Exercises Worthwhile for Novices?

The first and probably hardest part of the question is to actually define a novice. I'm not going to give a definitive set of numbers for the major lifts as this can be misleading. Trainees can see massive improvements in musculature during their first few months without touching the big three lifts. Most weight bearing exercise is usually above and beyond what the trainer will have experienced thus far, illiciting rapid adaptations in musculature and strength. Instead I will simply define a novice as someone who has very little or no understanding about the general movement patterns needed to create changes to their physique. There is little or no understanding about training protocols such as volume or frequency or even how to train specific muscles appropriately. 

Onto the second part of the question: are isolation exercises worthwhile for novices? The novice should allocate most of their training time and energy to learning the basic training movements: push, pull, squat and lift. Learning these properly as early as possible will put them in good stead for future training. These exercises will also provide the most carryover in strength to other movements both in and out of the gym. 

However, I also believe that a lot of time should be spent on isolation exercises to further develop movement patterns and practise 'contracting' specific muscles. One of the key differences between a novice, intermediate and advanced trainer is the ability to focus on and prioritise certain muscles during both compound and isolation exercises. The quicker this 'mind to muscle' contraction is established the quicker the trainer can then potentially progress from novice to intermediate. Over-training becomes more important as the trainer becomes more advanced, it is not something to worry about in the novice stages. 

The novice trainer should first and foremost concern themselves with learning and improving technique in the main movements (push/pull/squat/lift). Weight should then be added in a mostly linear fashion to each main exercise, whilst dedicating perhaps a third of time in the gym to isolation exercises. The novice should use this time to learn which muscles contract during certain exercises and more importantly to reiterate the contraction or 'feel' of the muscle during certain movements rather then simply moving weight.

Ross Newham - Natural Aesthetics