Hi @fostc80857 , OK the misunderstanding is because of your use of the word “files”. With KNIME the output from nodes is generally referred to as tables. When you say you want “16 separate files” I took that to mean that you want to write to 16 separate files… 
If you need different nodes hanging off each row filter so that you can analyse each category in different ways then a loop won’t be the solution. A loop would work if you want to transform all your categories on a one at a time basis and the transformations are the same for each. Typically though a loop isn’t an ideal construct for performing manual analysis within each iteration of a loop. You can step through, but it is a little painful and you cannot see the output from more than one at any given time.
As it stands with how you have described it, I cannot currently think of an alternative to the individual row filters that you are using. Ideally KNIME would have some form of “grouped row splitter” where a column value would define the rows to be directed to each of a variable number of output ports similar to the way a case switch acts with a flow variable but unfortunately it doesn’t.