I wanted to post this here but posted somewhere else 

My math still tells me is better to skip tiers. Here what I got doing it on my tower:
T6 3
️ to T7 - 75.8B
T7 1
️ - 10B
T7 2
️ - 15.6B
T7 3
️ - 22.3B
T7 3
️ to T8 - 621B
T8 1
️ - 82.4B
T8 2
️ - 128B
T8 3
️ - 183B
T8 3
️ to T9 - 5T
Total spent on updating from T6 3
️ to T9: 6.14T
T6 3
️ to T9 skip cost 5.6T
My math still tells me is better to skip tiers. Here what I got doing it on my tower:
T6 3
T7 1
T7 2
T7 3
T7 3
T8 1
T8 2
T8 3
T8 3
Total spent on updating from T6 3
T6 3