it ain't the first time an aftermarket manual was wrong.

you don't need to remove the valve covers or the rocker arm bolts.

You will have a false indication if the cams are beign loaded by the
valve springs.  So, that is why they want the rocker shaft/ cam
followers loosened up.

 Cause it's a BS shop manual. There is NO reason to do any of that and I
laughed when I first read that in those manuals. Wonder how many hours this
has cost backyard mechanics! If this was in any way important, the factory
manual would say this as well.

While I'm on the subject, spend the money for a dealer T-belt that has
timing marks on it, the amrks on the covers are inaccurate at best.