That is bad practice IMO because it makes it easy to accidentally introduce bugs and produces code that a reader will misinterpret, making it harder to find bugs.

The better approach is to always compare against FALSE, because that avoids the ambiguity of == TRUE only catching a single truthy value out of the millions of possible truthy values, contrary to the well-known semantics of C.

If you really need to distinguish between 1 and other truthy values, then just compare against 1 explicitly. Don't muddle the concept of truthiness.