yeah, 8h is REALLY light.. I haven't used an H in a loooong time...
I used to sketch anywhere between 4h and 2h really lightly and then go in with hb then keep darkening up, up to 6b.
Now I usually start out with HB or 2B, block in what I'm doing, then use between 6b-9b to put in my darks.
I don't ever use H's anymore, but I heard they're good for really light parts by highlights.
I was just thinkin about this a few minutes ago...
If I'm trying to shade a sphere, and I use a 2B and try to draw it really light even up to by the highlight it looks wrong... so... I'd draw the dark part, then use an HB or 2h to draw that light-but-not-quite-a-highlight part.