Here is my list of techs that I have skipped or am planning to skip. I think that you're correct about 8 in HMA.
Tech that you can skip in each age prior to InA:
BA: 5 (Growing, Tools, Stonework, Woodwork, Craftwork)
IA: 5 (Iron Works, Handicraft, Sewerage, Agriculture, Plowing)
EMA: 7...