I can't speak for how the union does it. I'm a non-union plant electrician; here working any shift and weekends as needed is just part of the commitment apprentices agree to when they accept an offer to become an apprentice. They need to go where they will get the best learning experience in order for us to turn out good electricians.
That said we don't jerk them around; typically they rotate plants/shifts once a year, unless there is a valid reason (i.e. training or business need). They need a fairly regular schedule because we also expect them to be taking college classes while working. However, we don't make allowances for babysitter issues, kid's soccer game, etc.
While it is a big commitment that may be inconvenient at at times, it will be well worth it once you're done.
That said we don't jerk them around; typically they rotate plants/shifts once a year, unless there is a valid reason (i.e. training or business need). They need a fairly regular schedule because we also expect them to be taking college classes while working. However, we don't make allowances for babysitter issues, kid's soccer game, etc.
While it is a big commitment that may be inconvenient at at times, it will be well worth it once you're done.