As far as what I gained, 10lbs over ~21 months. But that came with 20lbs fat.
Realistically I would say 1/2lb a month lean mass with another 1/2lb fat is reasonable, and very manageable. Over a year, say u bulk like that for 10 months... thats 5lb of fat. U take 2 months to cut, thats more than enough time and u shouldn't lose any strength. Or u can get even leaner than u were when u started. Etc. I think a lot of people get lazy/irresponsible with their bulks... lord knows I did

U have to treat a bulk like a cut in the opposite direction. Watch the scale, count calories/macros, adjust when u need to etc. IMO