Background:
I started working through MMAsherdog's "ultimate course" that is offered by BTS. When discussing BB play on the river as the defender, he outlines that the two factors based on which we are calling are always (i) hand strength and (ii) blockers. Against small sizes (and a wide, merged range), hand strength is more important. Against large sizes (and a narrow, polarized range), card removal is more important and specifically we want to block the value part.

He outlined that we always need to be aware of
1. what is the top of our range in terms of hand strength
2. what is the top of our range in terms of blockers

Questions:
I know that in theory, we can never fold our top range. Not all spots will lead us to defend based on MDF=1-a, but we will always need to defend some portion of our range. I always thought about the "top of my range" as a unidimensional concept but his video made wonder whether there are actually two types of "top ranges". The top of our range in terms of hand strength and the top our our range in terms of blocking potential.

So do we always have to call our best hand in terms of raw hand strength and our best blocking hand?

Attempt of an answer:
My current understanding would be that the answer to this question would need to be "No, not always". I would say that sticking to this two-dimensional definition of "top of range" is very helpful, and that there are spots where we call entirely (!) based on one of the two dimensions.

SPOT 1: Nuts/air vs. bluffcatcher, we face an overbet on the river as the defender. Here, all of our hands lose to any of the bettor's value hands. So needing to defend the top of our range in terms of hand strength makes no sense at all. The top of our range is exclusively defined through card removal and we call those hands that block the value range (priority 1) and unblock the bluffs (priority 2). Is this true?

SPOT 2: Flop goes c-bet/call. Turn goes check/check. On the river, two condensed ranges full of medium strength SDV hands and air play against each other. We check, IP bettor bets 1/3 potsize. Here, the bettor's range is so wide that the effect of card removal is marginal. The top of our range is now exclusively defined through raw hand strength. Is this true?

SPOT 3: But what about this one? We land on the river with no heavy range asymmetry, no player has a heavy nut advantage, the river is a neutral card. We face a 2/3 potsize bet. Do we need to call our best hand in terms of hand strength and our best blocking hand here?