I know two older photographers who have washed fibre prints for years just as you described with the only difference being that they left them in the bath overnight. Their old prints are fine but one of them got into big trouble with his wife when the fixer damaged the enamel and they had to have a new bath installed. Some women are so blind to the important things in life. :)
Les; not all of us are blind to the important things :D
With regard to fill and dump with prints, this is another area that is currently popular. Check Bruce Barnbaum writtings, other threads on this site ; and i know that Jonathan Bailey also uses this method.
I'm not likely to ever want to use this method as I was lucky to have been sponsored with a 20 x 24 archival washer although it is excellent for photographers who have no space or enough money to purcahse one of the monster washers.
well, les and i are still on the same page. I don't use this method either, our washer is not archival, but it is one of the huge monsters. (so i am not sure if I am up one or down one on Les :p
However, as i also have several large sinks , lots of trays and several tray shipons , i tend to use those as well.