So, my experience (which with $2 gets a coffee at Tim's):
Admin will suck up the equivalent of 1/2 to 1 day per week. There's a lot of things that CO can't delegate, or there are things where, even if delegated, the CO still has to review or at least maintain SA on. Assuming the average of those, that's 39 days a year. I'll include the monthly (in not more frequent) brigade meetings for an evening in that tally.
There's the infamous one weekend a month - call it 2.5 days for eight months of the year. That's another 20 days - some of which will be in unit, some will be Bde inflicted PD.
There are ceremonial and representational activities. Even at a half day a month, that's another 5-6 days a year.
And there are the pop-ups, the things that are not scheduled, not planned, like the MP investigations requiring a reply, the queries from much higher HQs about what Bloggins did; the summary proceedings etc etc that are easily a day every month, another 10-12 days a year.
That's easily 75+ days a year. If a CO commands a geographically dispersed unit, with subunits more than 150km away, add in travel days.