I usually just make a formula and ctrl+d whatever rows I need to do.You can also CTRL-click the plussy thing, and get a menu of a bunch of options for filling down. Great if you have to populate a pattern 1000s of times (for example, you want to fill a column starting with 1/1/2010 to 12/31/2025 and don't feel like dragging for 5 minutes )

In terms of general playing with excel lately I've been using indirect a lot. It took me a while to get working but I like this guy:

=AVERAGE(INDIRECT(CONCATENATE("'D 190308-3'!",ADDRESS(16*($A2-1)+2,COLUMN(B$1)+4))):INDIRECT(CONCATENATE("'D 190308-3'!",ADDRESS(16*($A2)+1,COLUMN(B$1)+4))))

I have a sheet of many different sets of 16x24 data sets and on a different sheet I want to average each set of 16 rows for every column, then have the next row be the next 16 sets, etc. I think you'd normally do this with a pivot table or something but I couldn't get it to work right and it was a lot of clicking, this is nice because I can just keep copying the analysis sheet for every new dataset.

thrashD, I might be a little confused about what you're doing, but why can't you just =A1-A2? All of my datasets are text files that have a first column of the form "3/11/2019 11:38:21 PM", and when I import it into excel it naturally converts it to a date, and I can subtract them just fine. So for instance A1233 is 3/11/2019 11:16:44 PM, and A1249 is 3/11/2019 11:38:21 PM, so if you do =24*(A1249-1233) the result is 0.72, because 0.72 hours elapsed between my runs (excel time differences are in days). Unless I'm wildly misunderstanding this solves your problem. You can certainly do the more involved things, but if you have something of the form mm/dd/yy hh:mm:ss you can just subtract.