Thanks. Downloading LAPACK and counting the number of source files with intent using the Windows command findstr -i -s -m intent *.f *.f90 | wc gives 30 30 564 (so 30 files with intent), and the output of findstr -i -s intent *.f *.f90 is lines such as
src\SRC\cgedmd.f90: CHARACTER, INTENT(IN) :: JOBS, JOBZ, JOBR, JOBF
src\SRC\cgedmd.f90: INTEGER, INTENT(IN) :: WHTSVD, M, N, LDX, LDY, &
src\SRC\cgedmd.f90: INTEGER, INTENT(OUT) :: K, INFO
src\SRC\cgedmd.f90: REAL(KIND=WP), INTENT(IN) :: TOL
so they are using argument intents in a small fraction of their procedures. Presumably pull requests could increase that number.