I've been storing and re-using my TF-3 up to its claimed capacity or when a snip test produces excessive clearing times. AFAIK, this is safe for most fixers, including TF-3. Some fixers do go bad quickly, though. The usual symptoms are white particles falling out of suspension and/or a rotten-egg odor. (TF-3 has such a strong ammonium odor that I doubt if you'd be able to detect a rotten-egg odor over that, though.)
I have been using TF3 for a long time - It usually lasts a few months on the shelf at most - I get about 17 8x10 film or 40 8x10 RC prints /Liter - It does not have the capacity of TF4 or the price. - Homemade - TF3 is a great value.
My photos are always without all that distracting color ...
I was thinking in terms of two bath fixing in film processing. When using acid fix, I would have two bottles of working solution which I would go on to re-use again. I just wondered if the same applied to alkaline fix.