Are most acting jobs full time or part time?

They become full time once lucrative.

Part time. think about it.  One a TV show you may have 5 to 10 actors who are regular and appear every (or most weeks.)  All the rest of the roles are people who come in and work for a week (or less) and their job ends.  Same with making a movie.  Most of the roles there are only for a short period.  If you are making a commercial, you get one day of work.

The majority of people who act also have other careers.  We get some who manage to land a role that they can live on as long as the role last.  And the occasional actor who gets a lead in a successful show or movie that runs of years (or has sequels) and they can retire on the royalties from the show.  But they are the exception. 

If you have the acting skills, you can make a living at acting.  There have been many people who are good character actors, able to move from role to role, show to show and make a decent living doing it.  

But the majority of actors have to have other sources of income to survive.

Most members of SAG/AFTRA don't make a living at acting.  Some barely make enough to keep the health insurance.  There were old Hollywood stories about actors meeting each other in the unemployment office.

All should have a steady source of income and be prepared to take on any role that pays.

Anecdote I read:  A PA was told to pick up some production trailers.  He went to the trailer rental company.  It was owned by Lyle Waggoner.  The PA was surprised to see him working there and was a bit star struck.  After completing the paperwork, the PA asked him, "Do you do this for fun?".  Lyle replied, "This is my job.  Acting is for fun".

Acting is “gig work” since every acting job is temporary.  Attempting a professional acting career is like starting and running a company where you are the product being marketed and sold. Getting one acting job does not guarantee you’ll get anything else andybtime soon.

So the actual acting jobs - where you are on set or stage - is only part of the career.  A professional actor needs to work on the business end of things as well.  This includes understanding legal issues (contracts, unions, taxes); marketing (headshots, resume, show reel, website, social media) and networking.  The only reimbursement an actor gets for this business work is increasing the chances they’ll get an acting job.  But it’s essential for a professional acting career.  And there are a lot of scams and rip offs that prey on people who don’t understand the realities of the industry and mistakenly think they can just be “discovered”.

So it’s a huge investment of time, effort and money with no guarantee that you’ll ever make a living at it.  That’s the nature of the business.

All acting jobs are temporary and every one could easily be your last.

An acting job can last an hour, a day, a few days, a week, a month - a few may last for a couple of years but those are very, very rare.

Almost all professional actors have to work an 'ordinary' job alongside acting, just to afford to live.  They fit in whatever acting work they may get, along with rehearsals, workshops, masterclasses, research, line-learning, etc, with their day job.  Typically, an actor will never get more than maybe 7 days' paid acting work a year.

It's a very tough career choice!