Two off-ship activities a day on a ship of 200 passengers or fewer, and each one is either a landing or a Zodiac cruise. Ships under 100 passengers can sometimes squeeze in three or four. Ships over 200 usually manage one. If you've seen six or seven landings a day suggested anywhere, that isn't real and it's worth correcting before you book on the strength of it.
The other number worth holding onto is that a landing is 60 to 90 minutes, not a full morning.
Count landing days rather than total days when you compare itineraries. A 10 day sailed voyage spends about four of those days crossing the Drake, so you're looking at roughly four or five days of actual excursions. A longer itinerary buys you proportionally more of the thing you came for.