You are omitting an important point: Before the washing cycle starts, you have to rinse the tank and the film to remove any fixer still clinging to it.(posted 8992 days ago)Well, it may not be enough to call it archival, but I have been using this method without bothering to dry my tank and film between the individual steps without becoming aware of any problem with my negatives for the last 10 years. My only deviation from this method is that after the 20 inversions, I bath the film for a further few minutes in demineralised water with a wetting agent, because at my place, the water is very hard.
There has been a test of the method in a German photo magazine around the time I started using it. This test confirmed that the value of residual hypo in the wash water was the same value as that measured for the water before washing. So the conclusion was that the method should be OK.
Furthermore, consider that the effect of washing is exponential. If one wash leaves 10% of the hypo that is there in the beginning, and the next step does the same, you are at 1%. A further step will take you to 0,1% asf. It is certainly a good idea not to leave the tank half full between the steps, but to dry it is certainly overdoing it.
The exponential decrease means that using the same quantity of water, the effect will be greatest when you wash as often as possible with the quantity of water used for each wash as small as possible. I remember having read an article to that effect, with a detailed mathematical derivation, in an applied chemistry journal some 15 years ago. The authors impressively showed that the effect is very different when you use one litre of washing solvent all for one wash, two washes at 500 ml, three washes at 333 ml ...
The Ilford method takes into account that the process of wahsing the hypo out of the film is a diffusion-based process, i.e. it will be the slower the smaller the concentration gradient, or the less hypo is left in the emulsion. To compensate this, each consecutive step takes longer to reach the equilibrium where leaving the film in the water for longer will not make any significant difference any more. Note that the increase in the number of inversions suggested by Ilford is exponential, too.
So if you still have doubt about the method, just add a further step with 40 inversions, and you will surely be fine (except maybe a sore arm).
As I see it, you are much more likely to contaminate your film with your fingers after having washed it it unless you wear gloves when handling the fixer and discard them when handling the film.