The overall length of endmills is a relatively loose spec:
+/- 1/32” in ANSI
+/- 1mm in ISO
That is too wide for dynamic repeatability if you are counting on backup screws. We know it is easy with tool presetters and tool setting probes to update offsets of varying stickouts, but you can take a stable process and make it unstable by changing its frequency. If you are using high performance cutters with premium toolholders and balancing assemblies, but not controlling the tool projection, you are missing a huge piece of the puzzle.
Also, if your toolholder uses a weldon flat for pullout control, how repeatable is that flat location from endmill to endmill? Good question to ask.
Sharing information about high performance milling technologies, the result of 30 years of research.