i use 2 baths for everything.

the problem with the fixer test kits is sometimes
they are made for a specific fixer, and will give you a false reading.
i use sprint speed fixer and when i use edwals hypo check it gives me a
indication my fixer is exhausted when it isn't ...

the point of the 2 fixer baths is that the 1st one does all the work, and the 2nd one does "sloppy seconds"
and if you use 2 baths, even if your first one is close to dead, #2 will completely fix the film or prints ..

YMMV

have fun!