How often does one need to do these sessions?
Ive also got scuba weight belts that I can strap around my waist or across my shoulders to increase resistance on things like push-ups, chair dips, pull-ups, etc. I can pile up to maybe 40 pounds on those.
Back when I owned a gym, I'd recommend that people come in and work out pretty frequently until we got them through the learning phase and had all their numbers dialed in (and I used to offer a very cheap starter package for this purpose), but that's only important if you're looking to make the fastest progress possible. Once you have solid form and have the weights dialed in so that you're hitting momentary muscular failure in the appropriate time window most peoples' workouts can be very infrequent and still see progress. This is especially true if you're doing any kind of martial arts conditioning or other activities that provide some significant stimulus to the muscles. There are other factors like your health, how hard you're able to push yourself in your workouts, and how well you retain motor skills when you don't practice.
To give some general guidelines, I try to do a high intensity workout about once a week and I find that to be pretty optimal for most people. Almost everyone can push their workouts out to every other week and still see regular, really good, progress - often only slightly worse than once a week. I've had clients who were slower to recover than the average who actually saw
faster progress working out at this frequency. I've also had clients see noticeably slower progress (but still progress) with a 2 week break. They were often, but not always, clients who had either a hard time maintaining good motor skills or who were unable to push themselves to a deep level of muscular inroad. I've also had clients who traveled a lot for work or were otherwise unable to train for extended periods, like 2-3+ months in some instances, and most of them still progressed - just more slowly. If you train regularly every other week, have good form and retain those skills, are in good health, and then take a 4-6 month break you really aren't likely to see any really big losses and might even see slight gains. Even if you do see some small losses you will get back to where you were and then exceed your previous strength levels pretty quickly if you get back to regular training again.
It's also generally true that the more advanced the client the longer they can wait between sessions. More experienced clients have more ingrained motor skills and can usually push themselves a
lot harder than newer clients. This means that they'd get a much deeper muscular inroad, which benefits from a longer recovery and they weren't going to be hampered by forgetting how to do the exercises.
One of the big down sides to longer breaks (more than about 2 weeks) is that you'll start to lose the metabolic adaptations you've made to this kind of training and you can end up winded and feeling nauseated because you haven't lost any strength or skill, and can push yourself really hard, but your body has forgotten what to do to manage the metabolic impact of the work. And again, it also depends on what you're doing in between. For most people, the more they're doing other forms of training, and the higher intensity that training, the longer they can go between workouts.
There's a lot of variables here so feel free to ask for clarification!