Exercise combinations (or 'combos', if you will) are one of the cornerstones of an effective fitness programme. I use them all the time to build strength and muscle, by focusing on the large muscle groups when using weights or resistance training (as in this video, with Mick working out in the open air).
The key to creating effective combinations is to cover as many large muscle groups as possible during the workout, to exercise technically (a steady pace with a focus on the exercise being delivered) and to use the right equipment for the workout.
Also, combination workouts do not need to take a huge amount of time to deliver or to feel totally exhausting. It is possible to use of number of relatively short, mini-combinations to make progress, so long as these take place over a reasonable schedule (and are not spaced out to be unchallenging). So, choose the right equipment for what you want to achieve, make a plan that works best for you and get to it. You have nothing to lose except your lack of fitness!