NO, I must recommend DO NOT follow that advice.
That link is (very) old. It's from before Squeeze. When Lenny was the current stable (2009-2011) you could optionally upgrade to dash as system shell and use insserv to have a dependency-based boot. It wasn't the default because it was cutting edge at the time.
Since Squeeze, Debian has used dash and insserv by default. So dpkg-reconfigure of dash or insserv will have no effect at all. You're already benefiting from the faster boot these things provide.
I wouldn't recommend messing with your boot now nor would I have recommended it back then, unless you understood the boot process through and through. I also wouldn't recommend using readahead or messing with runlevels as these can be intrusive changes to your system. Trust the Debian developers to know what they are doing when it comes to the preferred boot process.
Ubuntu uses a totally different boot system to Debian's, based around upstart, that in many cases will boot faster than Debian. That's just the way it is, and Debian has some good technical arguments for why they don't want to go with upstart, at least not yet (I believe one of them is that it wouldn't fit with kFreeBSD, which Debian is beginning to support). Changing would be quite complicated. Ubuntu has done it, but Ubuntu supports fewer architectures/kernels and can change faster.
If you really want to speed up boot by 3x, go out and buy a modern Intel SSD. They are getting remarkably cheap now. And you'll gain sub-10-second boot times.