The issues are a bit technical, but it's time someone finally spoke the truth on these matters.
You're familiar with cartoon physics? That's the laws of physics that apply consistently in cartoons but nowhere else. Like when the Coyote can't fall in a Road Runner cartoon until he notices he is not standing on something?
I've discovered soap operas have a physics all their own that explains apparent temporal anomalies commonly observed by viewers. I call it my Theory of RelativeTV (companion to Einstein's popular Theory of RelativeVT--sometimes spelled "Relativity", but pronounced the same either way). Unlike the theory of RelativeVT, which no one understands primarily because the VT doesn't seem to stand for anything, the Theory of RelativeTV should be understandable by any soap opera viewer.
As with Einstein's theory, there are two basic scenarios: General RelativeTV, which is really useful only in special cases, and Special RelativeTV, which is more generally useful.
In Special RelativeTV, a viewer can be sitting in front of the TV seeing two events that seem like they should be co-occurring, but they are in fact separated by a half day, a day, or sometimes more. Clocks or sun position or the fact that one person is eating lunch while another is eating dinner are what typically tip us off to the effect. In extreme cases, whole weeks pass on a single 'plotline' (the Soap Opera analog of the real world notion of 'timeline') with players still thinking it's the same day, while others in other plotlines appear to be aging normally.
Newsgroup readers are quick to pick on these scenes as errors, but I think unfairly so. I prefer to assume there is a very hardworking and underappreciated RelativeTV Continuity Engineer working constantly to assure us of these effects because they are forced by Soap Opera physics. Rather than laugh and poke fun, we should be offering serious gratitude to their tireless efforts in this regard.
In General RelativeTV, we see the really extreme cases of RelativeTV. Soap Opera Physicists know in their hearts that the same math could explain both situations, but generally prefer not to bore their fellow watchers with such details, and sometimes even resort to 'watering down' the explanation. (Watering down is a technical term in which these RelativeTV effects are explained off as the effect of Genoa City Aging Water or some equally hokey thing that sounds good but neglects the obvious science behind the real effect.)
In the real world, Einstein's General RelativeVT is best illustrated by having one person get on a spaceship and travel very close to the speed of light for some distance, while another person remains stationary. (When the traveler returns, more time will have passed on earth than in space, so the traveler will be way behind in his soap watching.) In a Soap Opera Universe, spaceships are not necessary to create the analogous effects. It is sufficient to have a writer who is a `space case'. When that happens, plots diverge and later connect up, with characters experiencing the same kinds of awkward effects as our space travelers, except that since people on the soaps hardly ever watch soaps themselves, they don't really have any way to notice that something odd has happened and so they go about their business with one having aged more than another and hardly any mention of the fact.
For example, to draw on The Young and the Restless from the mid 1990's: It's probably unfair to say that Victor Newman neglected his son for four years, just because his son had aged that many years. In Victor's plotline, hardly any time had passed and he presumably just thought the child was growing very fast (like in the Robin Williams movie Jack). Victor's neglected offspring, "Little Victor", did experience more time passage, but [Big] Victor had no way to know that. And other characters in that same storyline each perceived and responded to time passage each according to their own point of view.
Also, rather than boarding a spacecraft in order to achieve time dilation (as might be done in Einstein's General RelativeVT), a more common mechanism for adjusting timelines in Soap Operas under General RelativeTV is to send someone to boarding school. As any observer of Daytime Science can tell you, however, the effects in the two systems are reversed. The spaceman returns from his trip having aged much less than those he left behind, while the boarding school student returns from his time at school having aged much more than those who shipped him off. But except for this small detail, the two effects are generally analogous.
The Theory of RelativeTV is intended to leave you relatively reassured that there are no actual physical contradictions in such plots, even though such plots are hard for a viewer outside of the character's frame of reference (for example, in the viewing audience) to understand.
A special note about Simultaneity: Einstein's Theory of RelativeVT really says that there is no meaningful notion of simultaneity when shifting between frames of reference. Each observer will observe consistent results, but it's hard to reconcile those results into a single coherent picture. By contrast, my Theory of RelativeTV predicts that, all-too-frequently, simultaneity will be the observed norm, independent of one's frame of reference. This result has been repeatedly documented: viewers have been known to give up on watching soap operas for long periods of time, only to return and find the plot apparently stuck in the same place as it was when they left. Plot motion can sometimes seem to come to a complete standstill for months or years at a time. (Such inertially driven plotlines are what drove me to create my Another Way Out site.)