Verbal is just hard... it’s really hard to create original verbal questions. We have tried doing that for the
GMAT Club tests and I can’t say the perfect by any means. The challenge is that if you make the questions exactly like the official guide questions, then nobody’s happy because they are close copies. If you make them completely different, most people argue that there are nothing like that official guide questions. There is very narrow middle ground between too similar and not similar enough.
Verbal remains to be best with official questions though personally, I have practiced with a variety of tests and while I found that verbal was indeed different in unofficial tests, the differences were minor. They mostly came out in HARD verbal questions. Unofficial questions tend to be a little wacky when it’s a hard level of difficulty. Official questions tend to increase difficulty through subtleties such as scope. However, I wouldn’t have too many concerns practicing with unofficial questions all the way into high 600s or basically until verbal 35. I personally scored V 42 and have never held official guide in my hands until after the test. That’s a huge mistake and I seriously don’t recommend that you do that but at the same time, it proves that you don’t have to have access to official questions to succeed on the verbal section of the GMAT. I have used Kaplan’s questions in my case and the only official questions I saw were in 3-4 GMAT prep tests I took.
For the record, I scored a 540 a few months after I started lazy prep and before kicking it into gear so I was not going from 720 to 750. On the test day I scored a V42 on the test day and have never held official guide in my hands until after the test. That’s a huge mistake and I seriously don’t recommend that you do that but at the same time, it proves that you don’t have to have access to official questions to succeed on the verbal section of the GMAT. I have used Kaplan‘s questions in my case....
Back to your question, not many test products are set up to be taken separately as sections (unfortunately as it is). However, I wouldn’t hesitate about taking any reputable brand of tests you have handy. I would realize that a few of the questions you may be taking are not perfect and the score you may get would not be perfect either because it’s not an official score but you don’t want to be stuck on the little things. If you get stuck a little things, you might as well stay home and not do an MBA. If you know the material, you will answer the questions. If you think a question is flawed, just search it on GMAT Club and you get a sense from the discussion whether it’s flawed or not or you can also ask in the discussion. I see too many people being too focused on creating perfect test taking environment and accomplish absolutely nothing

(My children do that. Instead of doing their homework, they organize their desk to make it perfectly clean but that is just an excuse not to do the homework. I’m sure if I have offered them to play video games they would not mind a messy desk

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