I use the Ilford Rapid Fixer many years.
I filter all my chemicals before each use.
It lasts well, in a closed bottle, glass only.
I do notice a deposit that lands on bottom.
I throw away bottles when i mix new fixer.
I use 2 Fixers for my negatives.
First for clearing, check with leaders.
Second make sure well fixed but not "over" fixed.
T-Max seems to "eat" fixers, needing longer times and lasting much less.
T-Max a beautiful film but somehow looks "digital".
Preference to rougher look in my images.
I mainly use Ilford HP5+, Kentmere 100,400 and Ilford Pan-400.