How SS is calculated and works

[Krindor]

do the tiers affect DoTs in anyway, ie damage output? or just the GCD

As far as I'm aware of there's no reason as to why it would be tiered, so my answer to this would be that it isn't tiered and each point is a gain, but the gain is quite low, at about 0.003 in comparison to SS being at 0.013 looking at it as stat weights.