Re: silly question about bleach
The part of the hair that is bleached is bleached for good. But the whole process has to do with hair cycles.
What happens is that some of the hair may still be growing when you bleach it, so as it grows and what was below the skins comes above the surface and that part will be dark. Or the hair may already be in it's last stage and ready to fall out, the new hair behind will push it out and that hair will begin to emerge and will be dark- this could happen the next few days after bleaching.
Facial hair has one of the fastest hair cycles on the body. All the hairs are not the same part of their life cycle at any one time.
If one has relatively little facial hair and it's quite short, it could be a month before enough dark hairs have appeared that they need to bleach them again. If the density and length are a lot more, it can be every 1-2 weeks - only a fraction of the hairs might be dark but as there are a lot, enough that they will be obvious.
You won't know until you do it.