Complexity = M x G x W x S x K x Cxt x Tty x Owhere
M: number of machines and UNIX platforms AIX, HP-UX, SunOS, Solaris 2, IRIX, ULTRIX, OSF/1, Convex, (Linux ?) G: number of desktop types Plain Motif, Openwin and desktops like COSE and HP-VUE W: number of window managers mwm, twm, fvwm, dtwm, etc. S: number of shells sh, csh, ksh, bash, tcsh, zsh K: number of keyboards PC-like, NCD-like, VT-like, HP-like, SunOS-like, etc. Cxt: number of contexts telnet, rlogin, klogin, rsh, etc. Tty: number of terminal emulator types VT100, VT200, xterm, etc. O: other factors number of terminal devices, network aspects, etc.Then the complexity represents a bog number of different behaviours!
But, we need something, otherwise, it will take a great amount of time for each user to set a proper and consistent environment