Oh yes, I log the daily weigh-ins but I don't rely on them, only on the weekly weigh-ins.
For instance, I gained 2 lb this morning without any reason. Hopefully they'll be gone tomorrow.
I don't have "trends" over 10 days in my spreadsheet, but weekly total and daily averages for each week.
It's basically very similar to your system.

I have about a dozen or two formulas in my spreadsheet, every nutrition and body health formula I could find, really.
You can view or download my real daily spreadsheet from Google Drive (no account required.)
I just input my daily weight each morning (also in column B) and everything else is automatically filled in. The annoying spreadsheet even highlights a weight gain in a different color to shame me... ;)

My old weight records don't start pretty, but I am now happy about where it's going. I didn't expect to be going that far.