I haven't used a mummy bag for a personal trip where I wasn't intentionally testing a bag for a product review or was in deep freeze winter conditions (< -15 deg F), in 40 months or so.
A lot of this in the past 12 months has been a newfound appreciation for synthetic fill and the process of testing the new synth quilts that are coming out this year here. So, I have an 11 oz quilt that I'm using for "real summer" (warm!) conditions, usually paired with a cocoon pullover or the new vest. For most "3-season" conditions down to freezing, I'll use the 20 oz version of the same quilt, with a cocoon hoody and cocoon pants.
For temps down to about 10F, I'll use the same clothing with both quilts, layered.
Below that, I use the 11 oz quilt over a 23 oz down quilt, and add a down balaclava and VB clothing. That gets me to 0-10F or so depending on my puffy clothes.
Then it's time to build snow shelters or haul out Mr. Warm: A WM Kodiak SMF, which has the girth to wear a puffy parka and pants to bed. I used this, VB clothes, a patagonia DAS parka, and ID primaloft pants for a crossing of yellowstone in winter where the temps dipped to -37F, and slept "comfortably cool".