How many backlink tiers

Is any more than 2 backlink tiers more effort than they're worth?

I've made link building a diagram with knowledge collated from BHW and it's got 3 tiers.

Tier 1 - Original Content - Web 2.0s, Articles etc
Tier 2 - Spun Content - Web 2.0s etc
Tier 3 - Link blasts with UD / Xrumer

Would it just be as effective with 2 tiers?

Tier 1 - Original Content - Web 2.0s, Articles etc
Tier 2 - Link blasts with UD / Xrumer

It would certainly be a lot less work.