It might depend on the version of 10.4 you begin with.
For instance, when I install my iBook 10.4.3 and update to 10.4.11, Software update then wants Java release 4,5,6,7,8 & 9. A real pain but I have these on a server at home.
If you start with a late 10.4 from an Intel Mac, say 10.4.10 on a Mac mini (Mid 2007), then many of them are probably included on the original install.
It does surprise me that each release since release 4 is around 80MB but these are Universal Binaries. The exception is release 8 which is a paltry 1.6MB.
Release 4 was available as separate PPC and Intel builds at 30-40MB each.
Exactly why there isn't a single Java Update for 10.4.11 that installs the latest revision in one step, only Apple knows.
EDIT: General rule of thumb: If Software Update says you need it and ticks it automatically, you DO need it. You also need to re-check after it's installed.
One trick that may be handy is that 10.4.x was the first OS to allow you to queue installs. Unfortunately for Java, the second last thing the installer does (writing package receipt) needs to be done before you can launch the next Java Update - this saves rebooting, which isn't required for Java Updates.
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Yamaha DT200 history