The right personal trainer is a great tool for anyone (beginner, novice, intermediate, or professional).
Even if you are a coach/trainer it is easy to go easy on yourself - it's natural to work harder for a coach. Working with a coach is a great way to keep yourself honest, accountable, tighten up your skills, & get better. A face to face (1-on-1 personal trainer) is a great tool if you can afford it. Most sessions are circa 50 minutes. Now to manage the time. The good trainers will be prepared and write out your plan in advance. We will assume they have a good plan; now the limitation to the plan is time. For instance, a sample daily plan could call for: Tension planks, deadlifts, & kettlebell swings. You get the planks done. You notice you are extra tight from your marathon chair sessions at work. This time your body needs longer than your normal to work out the kinks. By the time you prep (mobilize/stretch), practice your reps, then complete deadlifting- no time left for swings. Another example could be, it is Squat or Bench day. You are ready for action, but some guy is curling in the rack (squat rack or bench rack, I've seen both). Time could be preoccupied with "busy work" - but that isn't going to help contribute to our main focus of the day. Waiting for this guy to finish with his curls takes away from YOUR reserved time and puts you behind schedule; you probably won't complete what has been prepared for the day. Or perhaps learning/polishing a new strength skill - maybe you need a little more time to feel out the move. So far I have described some examples with the best case scenario (your trainer is prepared). But unfortunately, my experience of over 20 years in gyms across the country, has witnessed the majority of trainers will "wing it". While winging it - they will aimlessly wander the gym looking for what is open and try to jump on it. And they will go on this wander for your entire session.. "Euh, what's that over there.. hmm.. let's try the upper dorsimus machine!" *Looks around*, we still have 40 minutes, "How about the Leg Press!" "Nobody ever uses the rower, let's grab one!" The have minimal plan they "fill" the time. Regardless of the quality of your trainer's planning capabilities - maybe you are stuck in traffic get to the gym 15 minutes late; now you only have 35 minutes for your session.
Now in contrast - Let's say you have the plan on your mobile device. You have video demonstrations of the exercises. If you can get it done correctly in 30 minutes - fantastic! If you'd rather take your time and enjoy the down time/the "me time" & stretch it to 90 minutes -enjoy: Workout at YOUR pace!
Check out available programs at: www.alwaysgetbetterstronger.com/programs