How can you tell if you're overreaching? Here are simple guidelines:
90% of the time, thinking should take 2 minutes or less. (1 in 10 things goes past 2 minutes.)
90% of cases that take longer should be under 15 minutes. (1 in 100 things goes past 15 minutes.)
90% of the cases that take longer than that should be under 2 days. (1 in 1000 things goes past 2 days.)
Next steps should be fast. You shouldn't be stuck for long periods of time. ("Long" means longer than the amounts of time above. A main point of this post is that people have the times wrong and are routinely stuck for a few hours and don't realize how long and bad that is.)
Most stuff you do should be small and easy. If it's not, break it into smaller parts (so that you can be making progress frequently by finishing one little part) or find easier stuff to do.
If someone says something, you should usually have an idea of your reply within 2 minutes. A clarifying question is fine as a reply. It doesn't have to be a big thing. Or if you are going to give a big reply where you make 5 points, then you could think of each point as a mini project and figure each one out in 2 minutes.
If you're writing an article or novel, most steps should take less than 2 minutes of thinking before you do them. A paragraph is a reasonable step. You decide what the next idea will be, then you write the paragraph for it. If you stop midway through the paragraph, starting again is another step. If you need to do planning for the paragraph, e.g. checking your notes about the plot and your chapter outline, those activities are also steps. If you spend 10 minutes reading your notes before starting a paragraph, that's fine, that's time spent making progress on the activity. The time limits are to deal with the time you aren't doing anything, where you're just thinking and not actively, directly getting anything done. When the breaks between actively doing stuff are larger than these time limits, that indicates it's hard for you and a lot of problems are coming up and you're probably making a bunch of mistakes.
Don't try to cheat. This will only help people who approach it honestly. Like if you think of a clarifying question in 10 seconds, just ask it. Don't save it for 1 minute 50 seconds to try to get extra thinking time.
If you're usually going near the time limits, something is wrong. Sometimes it should be 5 seconds, sometimes 30 seconds, sometimes 90 seconds. If you're frequently just under 2 minutes (or a little over and rounding down), you're probably overreaching. For the 2 day timeframe, most of those should only take a couple hours of time you actually spend on it. Actually spending a large portion of one day, let alone two days, should be much rarer. Two days gives you time to sleep on it, or leave it on the back burner for a while, wihch is good to do occassionally.
These guidelines are not exact but the simplicity and ease-of-measurement are major upsides. They can give you a ballpark of what to look for. Compare what you do to this and see if it's even close. I think people don't have much understanding of how long "too long" is, in concrete numbers, so this will help.