>>4420542You're not judging the exposure under safelight, you're judging whether it's done developing. The time that takes will vary depending on the paper and also how fresh your developer is.
Every paper I have used basically follows this curve. For ~10-30 seconds it looks like nothing is happening. Then it gets darker quickly. Then it will look like nothing is happening for quite a while again. If you leave it in a very long time (maybe 5 minutes) it will eventually start getting darker in the highlights.
Any time between b and c will look pretty much exactly the same. If the whole frame turns black that means you overexposed it. In that case you can pull it out early and throw it in the stop bath to prevent it from going completely black, but the result is your shadows will not be fully developed and it will look grey and boring.
If the unexposed parts of the paper start to darken right away (i.e. b and c happen at the same time) it means your paper is fogged. Either it is old and degraded or your darkroom is not dark enough.
