Well, yes, implementing progressive overload will result in strength gains. There are also rehabilitation prescriptions requiring them (I’m not a physio and don’t know the specifics here)
Are resistance machines optimal?
In short, generally speaking, No. Free weights require more muscle fibre recruitment, engage more muscles for joint stability & transfer over to sport performance and day to day movement more effectively. For optimal “Bang for your Buck” time investment, compound free-weight movements should be the priority for your strength training with isolation and machine exercises being “accessory’ or “supplementary” exercises.
“Free-weight exercises require that the resistance be balanced in all three planes of movement (sagittal, transverse, and coronal) and require the use of additional muscles to balance the resistance, as is required of movement during everyday tasks. So free-weight exercises resemble movement and muscle recruitment in the real world to a greater extent than machine exercises do. If you are training to improve athletic performance, which takes place in a three-dimensional world, advocates of free weights believe that training in a manner resembling movement in the real world will result in greater carryover to performance in the real world.” (Kraemer et al. 2007)
“Free-weights exercises tend to involve more supporting muscle groups than machines. Some will see this as a disadvantage (less muscle isolation) but in reality, if one wants to build a lot of muscle fast, it’s an advantage.” (Thibaudeau 2006)
Whilst offering more potential benefits than machines, free-weights require a higher level of technical proficiency and proprioception to perform. They also carry a higher risk of injury in the short term if performed incorrectly.
If you don’t know what you are doing, hire a professional to get you on the right path.
Kraemer, William J. & Fleck, Steven J. (2007). Optimizing Strength Training. Illinois: Human Kinetics, Inc.. p42.
The Black Book of Training Secrets Enhanced Edition By Christian Thibaudeau 2006 e-book p72.