From what I’ve watched and researched, new pilots would be on a reserve schedule. If you’re not flying, can you do other things in the mean time? Example- instruct, charters etc…
Short answer is no. There are multiple problems with that. First if you’re on Reserve you’re on call and expected to get to the airport in a timely fashion which you couldn’t do if you were flying elsewhere. Next pilots are restricted to how many how they can fly in a day, month and year and also require a certain amount of rest. If you were unable to fly an airline trip because you exceeded your time elsewhere or didn’t get sufficient rest that elsewhere had better be paying the bills because your airline career would be over. Further your pilot license is your pilot license. Do something stupid flying elsewhere, get violated and again you’re done.
This is why many airlines specifically restrict what other jobs you can have. Particularly if there’s flying involved.
Do the airlines discourage you from flying recreationally for personally purposes?
No, personal flying is not discouraged or prohibited, but you will not find many airline pilots that do it either.
Once you get spoiled by the equipment in an airliner, it is hard to go back to a little airplane. Furthermore, any accident or incident in a little airplane will need to be explained to the FAA and thus the airline. There is just too much potential for issues that could jeopardize our jobs.
Plus, I fly airplanes eighteen days per month. While I love my job, the last thing I want to do is fly airplanes on a day off.
There are many pilots that fly on their off time though.
As Chris said no and I do know a few who do, but not many.