Hi there!
I can't give you a number on how long you should read a passage, but I hope the following helps:
Yours is a common concern regarding RC. Timing is tight on verbal. You can see the clock ticking and feel under pressure to finish reading and start with the questions.
Resist this temptation.GMAT has quite a bit of illusory answers that seem right if you are rushing through the questions. When you read, make short, very abbreviated notes. Read well,
don't rush through it. Trust me, it will save you time later on. There is nothing to gain from skimming the passage and then revisiting it for a question just to re-read it again! You'll lose much time.
Instead, stop thinking about the timer and read as thoroughly as you can. It will take you about 2-3 minutes. Let's assume it takes 3. For 3 questions, you have about 6 minutes. 2-3 spent for reading. That still leaves 3-4 minutes. This might seem less, but if you have read the passage well, you'll most likely answer at least one question in about 40 seconds. That way, you still have 3 mins for the remaining two questions - which you will find easier with your thorough reading and notes.
Especially early in the test, getting answers right matters. Read the thread
https://gmatclub.com/forum/gmat-prep-software-analysis-and-what-if-scenarios-146146.html and
https://gmatclub.com/forum/600-to-740-all-about-timing-and-fundamentals-147029.html.. You'll notice that getting the answers right, especially at the beginning, is very important. If you are early on in the test, spend the time (even if it's more than the average available per question) to get them right. It will help your score. Getting answers right at the beginning and wrong later is preferable to the reverse case.
In general, I have found that taking longer on some questions is OK since you'll take shorter on the others. Don't hold yourself to the 1.75 min mark on every question. You can take as much as 3-4 mins too, if you know there will be some that you'll be able to answer in a few seconds.
Hope this helps.