This is a good question because the issues with your sentences are subtle and hard to articulate. TL;DR your examples are indeed slightly odd, but not because of the time itself.
The subjunctive past can indeed be completed with reference to the present:
If I were braver (in general), I would be standing on that bridge right now.
The pluperfect can, too:
If I had been braver (when I made some particular choice that affects my present situation), I would be standing on that bridge right now.
The pluperfect can also be completed with reference to the past:
If I had been braver, I would have been standing on that bridge yesterday.
The slight oddity in sentences (1) and (3), I believe, is the lack of a progressive element. In each of the above examples, I used either the conditional progressive or the conditional past progressive. That said, this seems to be a semantic requirement, not a grammatical requirement.
This also explains @Ben I.'s feeling about "I would get a better mark", with which I fully agree. To "get a mark" is a one-time event. Hence, you can either say you "would be getting a better mark" or "would get better marks", both of which stretch that action out over a period of time.
Similarly, a verb that implies a period of time is perfectly okay in simple present:
If I were more attractive, I would receive more compliments.
Why do these conditions appear to demand a period of time? I suspect it has to do with the ability to describe something happening in the present time. You can't say you "would get a better mark" at the same time that it's happening.
It's worth noting that both the subjunctive past and the pluperfect be completed with a conditional perfect (for the same reason, I think):
If I were braver, I would have stood on that bridge yesterday.
If I had been braver, I would have stood on that bridge yesterday.
The event is in the past and can be referred to with a perfective at the time of utterance.
Your second sentence is thus okay, except that in North American English, at least, one doesn't "have" an individual mark. Hence, this is fine:
If I had been more attentive I would have gotten a better mark yesterday.
(You can "have" a grade in a course, but not a mark on an assignment or test.)
Again for the same reason, you can also make reference to a hypothetical event using the plain old conditional to complete these phrases.
If it were sunny out, I would go to the beach. (But it isn't, so I won't.)
If he were more honest, he would get my vote.