Sadly, this same phenomenon can be incredibly distracting in a presentation. Have you seen it? The company logo nestled safely in the lower corner for 20 slides suddenly does a little dance on slide 21. The table that has been supporting a content build over several slides sudden shifts dramatically to the left. The headlines have a disorienting tendency to drift toward the top of the slide.
You might be thinking, "Oh, who cares about such a minor thing." But like so many small details in life - a dirty fork at a restaurant, a spot on your favorite shirt, a ding on your brand new car - once we notice them we don't forget them.
The good new is: Most of these slide twitches can be eliminated if you use PowerPoint as it was meant to be used. The basic slide layouts anchor your content consistently across your slides. I will occasionally see a slide deck that has been built entirely from text boxes floating on blank layouts, and I am dumfounded by the extra effort that was wasted creating each slide from scratch. It's like using a screwdriver to try to pound a nail -- yes, it might work, but why not grab a hammer!?! When you work with the basic layouts, your margins and headlines will not shift around from slide to slide.
That's not to say you have to use the "of-the-shelf" layout for size, color, placement etc. Edit the SLIDE MASTER and you can customize the look and feel, without sacrificing consistency. Place a logo on the SLIDE MASTER and not only will it automatically appear in exactly the same place on every slide - it will no longer be editable on each slide. That means you won't accidentally delete, stretch, or move it. Think of the graphic elements on the SLIDE MASTER as existing under a pane of glass. You can see them, but you can't touch them, unless you go back to the SLIDE MASTER.
If you have never explored to the SLIDE MASTER, it is very much worth your time. Not only will you better understand why slides behave the way they do and have more control, you will also save significant time because you can edit once and have it impact 50 slides. This is a skill worth pursuing.
After you've aligned the SLIDE MASTER to your will, you might still want to drop a graphic or other element onto several slides. A good example of this is a flowchart that you want to build in several stages, and you don't want to use animation on a single slide because you want the handouts to print individual steps on separate pages.
If you try to eyeball the placement of individual slide elements, you might get lucky. But there is way to create the look of seamless animation over several slides. (And if you started using PowerPoint, as I did, in the early 90's, you will remember this is how we did it before there was an option for "animation").
Create the FINAL slide in the series first. In the example of the flowchart, capture every step in the process. Be sure you're happy with it, before you move on to the next step. If you need to get buy-off from others on your team, get their OK before you move on to the next step (trust me, you'll thank me).
Copy your FINAL slide and place it before the final slide in slide sorter view. Edit the new copy to remove elements for the next-to-last slide. Then copy that slide, and strip off more elements. Continue until you have the desired steps in your series. Watch your series in SLIDESHOW and the slides appear to build.
The secret is that you locked in the placement for the last slide FIRST. Sometimes, you will realize you forgot something or need to make a modification that impacts all the slides in the series. The risk of "twitchy" slides is highest when we think we can make exactly the same edit in multiple places. If you need to adjust every slide in a series, I strongly urge you to modify the final slide and then repeat the copy-remove process.