Stories take time. They unfold over hours, days, week, months, seasons, years. . . centuries and ages if the story gets frisky (and they have been known to do so).
Complications ensue because of duration and pacing. Some complications can be finessed, and some can be tackled. Sometimes, they must be finessed, and others, they must be tackled.
Duration problems arise because some things require a period of time. If your story is rollicking along at a high pace, your characters must keep moving, and the period of time is longer than would allow for this, these things are obstacles and serious obstacles.
The faster the pacing, the shorter the duration. Cooking a meal is a problem when you are trying to flee pursuers hot on your trail. Raising a colt from breeding the stallion and mare to riding a fully trained war horse to battle is a problem when the foreign nations are already threatening war, and clearly making plans to raise armies.
Other stories are less time-pressed. If no one can travel during wintertime, the heroes may kick back and remind each other that the villains' location suffers worse snows and longer cold, so they will be able to move more quickly.
On the other hand, if the villains are holed up to do their villainy, winter may raise the stacks impossibly high. You may have to shift the time frame, so that the heroes face the challenge of arriving before winter does, or make the winter milder so it's a peril but not an absolute obstacle, or otherwise shift time around to make it fit. Possibly have them realize that winter's apparently arriving late, but they have to risk that it could arrive at any moment with a deadly snowstorm. Or possibly have an early spring and let the heroes risk the danger of a late storm.
Artistry is required with these techniques, though, because otherwise, the hand of the author stands revealed. A freak late snowstorm made them run for shelter? No, the author sent them running for shelter. Weatherwise souls warning about the signs of a freak late storm and talking about where to find shelter may help with the world-building, but some kind of world-building is needed to make it work.
Illnesses and injuries are more flexible. Even without magical healing, a character can recover more or less quickly, and most readers will allow more quickly than should be feasible. Provided, of course, that both onset or infliction, and the recovery are both in the time span when time is of essence. The king can assign the knight to escort the princess to her school because the knight is just recovered from his fight with winter wolves without raising any question; likewise, if the knight staggers into the school and collapses with the princess safe, he can be packed off to the infirmary while her studies go on and plausibly recover. It's when he's injured, and they stagger into the waystation, that the plot questions arise. Can he go on? Is it safe for her to go on without him, only with the rest of her escort? Is it safe for him to stay there when she goes on? How quickly he can recover? How urgent is her arrival time?
Pregnancies that go from conception to delivery within the course of a story are worse, since the time limits are much more rigid. Early births can only shave off so much time, and are hard on the baby. And, on top of that, they limit what the mother can do in that time.
At the other extreme, scheduled buses, trains, ships, airship, starship, and whatever forms of transportation are devised in the future can have the characters down to seconds. This gets -- more interesting the further in the past you go. The first strict timetable was that of the mail coach. It took passengers, and you had your timed lunch stop, and woe to the passenger who tried to linger a moment later. Prior to that, you could easily miss a means of travel, but not because you missed a fixed deadline. Ships, of course, were dependent on the tide, but past that, on the variable winds. Like a late winter or early spring, just missing -- or just making -- the ship requires setup to seem convincing.
When you make the ship, you have to factor in the journey time. Vagaries of time add to your complications. A modern ship, not only equipped with engines but with radios, is much more reliable than a sailing ship, dependent on winds, and with no way to communicate. Starships depend on what you determine for how they work.
But while starships and the details of their drives open up unusually many opportunities to blunder, all problems of duration do. It requires artistry to pull off these problems without the hand of the writer becoming altogether too obvious.