Developing decks requires a combination of different skills
Before you even open powerpoint, it's very important to learn how to develop stories (or what we call “dot dash”) which is a vertical format of the story you want to tell in your deck. Think of it as a series of bullets and dashes, flowing smoothly, with each bullet eventually becoming the title of the slide and the dashes becoming the content of that slide. The storyline is the very first thing you validate with your manager before you dive deep into the deck as it's easier to remove a bullet on word, than to remove a full slide that you spent 2 hours editing and filling.
To practice that, I would encourage you to check some of the trainings online (McKinsey has some good articles)
2- Communicating with charts and visuals
Knowing which slide to produce and which visuals/frameworks to use within it is another important skill a consultant should have. For instance, if the slide is about root causes and solutions, you would think of putting the causes on the right with an arrow leading to the solutions on the right. There are hundreds of ways to use visuals and to organize your slides and these are also important to learn.
There is a book called “say it with charts” around that
3- Powerpoint shortcuts
Notice that the actual powerpoint skills come in 3rd in my list as having a weak story and not choosing the right visuals is way worse than being slow at producing a slide.
Getting to the stage in which you're filling your slide with text and charts should be preceded by validation of the story and “skeleton” (how the slides will roughly look) with your manager.
Few shortcuts are helpful at that stage and I'm sure there are lots of articles around that. Few examples are copy format, copy width, distribute horizontally or vertically and align left/right/center.
Happy to give you a wider training on storylining and deck development if you want.