It depends on how well you can survive without repelling her boss attacks. Since the first round is endless, you should probably avoid getting hit by any means necessary, but at the same time, you get so many points at bonus that it probably justifies dying a bit earlier to spend more time at it. So it's a bit of a balancing act. You don't want to play it too safe or you miss out on points, and you don't want to go overboard or you get hit and lose the chain anyway.
Personally I usually prioritize survival, even on Normal, and ideally reach a point where you can get to bonus almost instantly after resetting. What I said in the previous post probably wasn't worded quite right. I wouldn't reset the instant you reach 500k, but rather as soon as a boss appears (which is a bit riskier of course, but probably better unless you're really bad at resetting). Or you may try to chain through the boss, like if you've got a lot of energy, or a strong charge attack, etc. I was saying before that Marisa has an easy time killing bosses on her own, for instance, so keeping the chain through a boss is much easier with her.
So really it just depends on your ability to survive the bosses. Reaching bonus is naturally a good thing if you can do it without getting hit.
And as for the rounds after the first, it's a similar deal. Score as well as you can without losing, assuming your intention is, in fact, to win. With some characters suicides may be worthwhile, and then it may or may not be worth going all out. I admit that suicides, and which characters can get away with them, are an aspect of the scoring I'm too familiar with. It's obviously a good thing against stage 9 Reimu on Lunatic, for instance, but elsewhere it's not so clear.
As an example, I was looking at a Lyrica run I did a while ago, and how a second death impacted my score. It seems like it was a bad thing, but could've been good if I'd played better.
In fact, from the looks of it I earned about 3mil from chaining over the course of the third round (which is crap, I didn't reach bonus once), used 15 spells, which was worth 2,250,000 in the clear bonus, and used 7 boss attacks, all of which were also reversals, which was worth 2,100,000. So really, if the death hadn't cost me the last 30 seconds of the second round (and however many points I would have earned in that time), it would barely have made a dent in my score. With better chaining, it could even have been a good thing.
