Consider the following:

<Name>A</>
<Dependencies></>
...
<Name>B</>
<Dependencies>A</>
...
<Name>C</>
<Dependencies>B</>
...
<Name>D</>
<Dependencies>C</>
...
<Name>E</>
<Dependencies>D</>

All these are installed to same base directory

What happens is:

1) extract A.7z
2) trigger patching -> scan the whole installation directory, open file by file and check if there is anything to patch
3) extract B.7z
4) trigger patching -> scan the whole installation directory, file by file check if there is anything to patch. Now it scans through files from A again, in addition to B
5) extract C.7z
6) trigger patching -> scan the whole installation directory, file by file check if there is anything to patch. Now it scans through files from A and B again, in addition to C
....

When extracting files from the 7z files the IFW should keep a temporary list of files which were extracted and apply the patch operation only for those files.