Way to change the default animation speed in PowerPoint

I would start with the final slide and work my way backward.

Create your finished table on a slide and then copy that slide and paste it before your finished table slide.

Delete a row from the table, and then copy that slide and paste it before the current one, etc.

As you go forward it looks somewhat animated (no flashy effects though) as you add one row at a time

All at Once doesn't mean what you think it does. It's meant for SmartArt graphics, as this page notes:

The difference between All at Once and As One Object is most notable in animations where the shapes rotate or grow. With All at Once, each shape rotates or grows individually. With As One Object, the entire SmartArt graphic rotates or grows.

It's easier to understand if you see each option in action:

All at Once:

As One Object:

One by One:

If you want multiple objects to be animated simultaneously, select all of them (either in the slide or Animation Pane), then select Animations tab / Timing / With Previous: