Do jobs in theatre lack continuity?
For the most part, yes. There are secure, full time jobs for technicians, directors, stage managers with reasonable salaries but for actors almost never. Many jobs in theatre are freelance. For each new play a new team of creative people are brought together and then move away on to their next job. Most directors, designers, writers will not be linked to a particular company or theatre and so they need to keep finding new jobs. However, if you want to work in administration, marketing or the like then there is much more likelihood of permanent work that is secure.