I want to improve on my knowledge of content, but I really want to at least get the ones right that I know how to do on the test first.
I completely agree. Can you tell me WHY you're getting the ones wrong that you know how to get right? Go back to the last test you took or the work you've done over the last week and create an error log. In that log, record the answers to these questions:
1) Why did I get it wrong (as specifically as possible)? (If there are multiple reasons, include them all)
2) What could I do to minimize the chance of making that error (or those errors) again? How will I make whatever that is a habit so that I really do minimize chances of making the same error again?
3) What are the right / best ways to do it?
4) Of the best ways, which one is the best way for me (combining both efficiency and effectiveness) given my strengths and weaknesses?
5) How will I recognize problems of similar type in future so that I can apply that "best way" to the problem?
Check the ones you got right, too. For any on which you got lucky but you didn't fully understand what you were doing, add those to the error log. (Even though you got them right, you can't be sure that you can repeat that behavior if you didn't fully understand what you were doing.)
It's great that you already know, for example, that you struggle with technique on algebra and number properties. Break it down even further than that. "I messed up on this divisibility and primes problem because I mixed up GCF (greatest common factor) and LCM (least common multiple). Why did I mix those up? What habit or process can I instill to help me remember not only the right way but also that this way is NOT the right way?" etc.
"I’ve been struggling between completing the test on time and giving appropriate effort to the questions I know I should get right."
There are NO questions we "know (we) should get right." There's only the ones we
do get right
in 2 minutes and all of the others. Getting something right in 3 or 4 minutes is NO BETTER than getting it wrong. I'd rather see you get it wrong in 2 min (or less). At least, then, you have a shot at getting the later questions right, the ones you haven't gotten to yet. And if you spend more than about 30 seconds extra on a problem, the chances that you'll get it wrong start skyrocketing. Do that enough and your score will plummet because you won't be able to get to a bunch of questions at the end. Let it go - if it's not happening in 2 minutes, it's not happening.
You're playing a tennis match. You're not going to win every point. The only way you're going to win is if you put yourself into a good position to be able to win the last point. Translated to the GMAT: you have to give yourself a chance to get at least some of the last few questions right. If you don't, you're not going to "win" the "match."
You're going to lose a lot of points. Up to about a 700 level or so, you only need to get 60% of the questions right. You can get almost half of the questions wrong! And don't forget that about 25% of the questions you're doing don't even count towards your score. You *really* don't want to burn 3-4 minutes on a question that doesn't even count!
Ideally, you should spend at least 1min on every problem (or at least 30sec on SC). If you can complete, say, a quant question in 40 seconds... check it and make sure you didn't make a mistake. (If you find yourself behind at some point, then just abandon the next hard question you come to - take about 20-30 sec to decide, "Yep, this one's really hard!" Then make a random guess and move on immediately. But that's only if you find yourself behind on time already.)
So, the timing stuff will help you somewhat, but it probably won't get you all the way from where you are now to where you want to be. You also need to improve on execution in quant (doing what you know you need to do). On some areas, you're fine and on others, you're struggling. Go back and look at that error log again and see what the patterns are. Then start working through those problem areas and explain to yourself, step by step and out loud if you can, (1) what to do, (2) how to do it, and (3) how you know that this is what you need to do next. (Really! When I'm getting ready to teach a new problem, I practice it out loud a couple of times - nothing better for making sure that you really know what you're talking about!)
Also, I don't like to suggest this because I have an obvious conflict of interest, but it may be the case that some private tutoring would help you to figure out both where and why you're still struggling in certain areas and what to do about those weaknesses. Private tutoring is very expensive, obviously, so I don't make the suggestion lightly, but when you feel like what you're doing isn't working for you, you generally need to try something new. Sometimes, the perspective of an outside expert who can watch you and diagnose what's going on is invaluable.
You mentioned that the course didn't suit your learning style. Can you articulate what your learning style is and how you learn best? That would be very valuable in general, and especially so if you decide to try to find a tutor (because you want to find someone who can teach according to your learning style).