I also use 6%, with 3% for inflation, for what its worth. And to counteract the "wow" factor of looking out to age 95 and seeing big big $$$ in the pot, I have a column right next to that that is adjusted for the 3% inflation, to bring it back to todays dollar. The spreadsheet of course includes my little pension, future SS for DW & me, and GPO for DW.
I really don't do much with spreadsheets anymore, just once a year when I knock another year of life off of the top. In the early years of my Early-Early Retirement, the spreadsheets were important. But, knock on wood, I think I'm past most of the potholes now.
For me, of more value for years now is my cash/near cash (Cash, CD, SB, IB) predictor that I input new data into every 6 months. I created it in Excel using y = mx + b. Predicting using rolling 12 months and 18 months data, when would that kitty intercept 0. Fun things happen when the kitty increases in value (when negative slope goes positive). The big slope-changing factor was the last child graduating college