TObin's Q & Equity Q

Hi, i dont understand the following extract from Schweser - the high or low q ratios can persist for long periods of time; in other words the expected stock price correction may not quickly occur".

Why is “persist for long periods of time” considered a limitation of this method?

How does "the expected stock price correction may not quickly occur"related to the q ratios?

Thank you!!

If things persist over long term, then you aint getting rich over night! It means the limitation is that the Q’s arent a huge signal to buy or sell.