I used to have a spare room I could use for a gym and so I had a press bench, dumbbells, kettlebell and even stationery bike...
...BUT now with kids I don't really have a spare room to use. And even if I had one, it would likely be used as a toys storage 🤷♂️.
So I had to improvise and my current home gym setup is this:
Yes, four rubber bands - laying down next to the desk in my office. I got these for Christmas.
I don't know if it's efficient equipment but it certainly takes very little space and it's kinda nice way for a quick workout.