The action roll system takes a bit getting used to as it works unlike many other roleplaying games.

Statistically, it tends towards mixed results - partial success outcomes will be common in your game, most likely.

Here's a page about the statistics of the system: https://takeonrules.com/2017/06/06/blades-in-the-dark-probabilities/ and as you can see the probability for "partial success" is consistently in the 30-50% range and in the 2-4 range where most character abilities will be most of the time, it is the most likely outcome.

Keep in mind that this outcome does not necessarily mean the character failed to accomplish his goal entirely. A 4-5 result can mean a partial success, but it can also mean success at a cost. In which case the player accomplished his goal, but at some cost or at the price of some complication.

For you as a GM, this is a powerful tool to drive the narrative forward and to let things more interesting than "ok, you got it" happen.

And, keeping with the nature of the action roll, this is a dialog between the GM and the player to establish before rolling the dice. Interesting ideas often come from players, who are there to tell a story as well, not necessarily to win.