For full instructions, read the Kodak Z-manuals (Z-131 linked from my howto) which explains when and why to wash; my howto is derived from the Kodak manuals and some experienced colour people here on APUG including PE.

Some of the kit instructions are extremely lacking and don't tell you when you need to wash, or put them in as a footnote that's not very clear at all. There's a long APUG thread (also linked from my howto) about the Rollei kit that discusses the washing issue and shortfalls in kit instructions.