(Writing Advice) Did you know that time skips are considered quite risky for new writers?
The teacher at my writing workshop was a miracle worker of an instructor and among the things she would often stress were the causal chain and the importance of pacing to make a tight story.
This is why she did not recommend time skips for beginner authors unless they really understood the risks. Not that it couldn't be done, but that many didn't recognize how much a time skip can mess up the pacing of your story.
Here are some risks of time skips:
1 ) Destroying your forward momentum: If you've spent a huge swathe of your story up to that point building the tension and urgency of the Big Thing that's going to happen in the future, having a time skip can stop that momentum dead. A time skip represents a reset of your story and is not advised if you're trying to ratchet up tension. A time skip, even of a few hours in a really tight and action-packed story with urgent pacing, can leave audiences scratching their heads wondering what happened during that missing time and why did the characters (and the author) take their foot off the gas?
2 ) Breaking your causal chain: In a tightly-written story, your cause-and-effect chains (aka 'causal chain') should be ironclad. Even if not everything is shown on the page, you, the author, should know how events and characters got to where they are at every moment, at both the large scale and the small scale. But when you throw in a time skip, suddenly you have a huge break in the tight line of your cause and effect. How did we get to where we are now? Why didn't we do something sooner? What has everyone been up, were they just twiddling their thumbs? It's all lost in the blank space and that can be unsatisfying for audiences if not handled well.
3 ) The need to backtrack to explain skipped events: This is in large part what killed the forward momentum of "A Song of Ice and Fire" for George RR Martin. Originally, ASOIAF was supposed to have a several year long time-skip, hence why the characters are so young at the beginning of the books. But then he realized, after publishing the earlier books, that he wanted to explore a lot of the events that would be skipped and the amount of flashbacks and backtracking required would be prohibitive. He decided to write through the timeskip instead, but that created a lot of deadspace and a less-tight story because not everything in those years really needed to be explored on a day to day level. (Frankly, I think he made a mistake by building this time skip into his outline, BUT that he was a skilled enough author that he should have trusted his instincts and kept the time skip, and just resigned himself to losing the chance to explore the events of those intervening years.)
If what happened during the missing time can't be quickly and elegantly summarized or referred back to, it might be better not to build a time skip into your story.
Raising more questions than you answer: How did we get here? What are we doing here? Why are characters in trouble that weren't before? Why didn't other characters intervene before things got so bad? Why didn't our heroes stop the new bad state of the world before it happened? Did everything the heroes did before to save the world not matter?
Many genre fiction stories will use a time skip after the Bad Guys have won a battle in the larger war in order to show the world plunged into a new darkness that the heroes have to face. For example, in The Force Awakens installment of the Star Wars franchise, the story was often criticized for having the bad guys of the Empire return without explaining why the previous generation of heroes were unable to stop this threat in the apparent 20-year time skip it took for them to return. This was quite unsatisfying for many audience members, to put it lightly and it seemed to invalidate much of the story the audience had been invested in up to this point, namely the ability for the good guys to stop the bad guys and save the world.
Just because you skip a period of time between one story and the next, doesn't mean you the author gets to skip over what happened during that time. If anything, you might need to work even harder to work out what happened in the missing space, in order to make your causal chain bridge the long span of that gap in a coherent and satisfying manner.
TL;DR Anyway, this is not to say you can't do time skips. Time skips can be great for purposefully wiping the slate clean, or purposefully resetting the story so a new evil can arise when your prior story has nowhere else to escalate too.
But a professional editor might caution against it if you don't really know what you're doing, and what can be lost when utilizing this particular plot device.
A lot of creators seem to think that a time skip will allow them to cover up sins and not force them to explain how a new world-state they wanted to explore came to be, but just as often it reveals the weaknesses of the story and demands more work of the author than simply following that time span linearly would have required.