Most of the time, but inconsistently, a player can sprint across a one block gap without jumping if either the block they are sprinting from or to is a top slab.

The player can run from right to left in each of the attached examples without falling down and without the need to jump. Each instance of a slab can be replaced with a trapdoor or stair and still works. Also works with doors, trapdoors, beds, slime blocks, brewing stands, and chests.

Steps to reproduce

1. Build the sequences of blocks shown in the picture above, or use other blocks like trapdoors or stairs instead of slabs. It may help to add a few full blocks before the first non-full block to give yourself space for a running start.
2. Run from one side to the other.

Expected result

You always fall into the 1-block gaps.

Actual result

Sometimes you run across the 1-block gaps.