How long before you re-bait?

I know this will vary according to method etc, but how do you decide when to rebait if things are going a bit slow?
When sea fishing I used to actually time it to about 20 minutes. I think with experience you get a "feeling" that you should re-cast, and very often you get a result, perhaps the bait had settled on some weed something. I think I tend to leave it too long, hoping something will happen, and have probably missed a lot of fish

About 20 minutes for me on the rivers.Although on freezing cold days I have left a worm on for ab hour and still caught.

As you've said it depends on what your fishing for & how

If there were carp feeding in front of you & you weren't catching then i'd be tempted to start rethinking bait/rigs. If i was confident the rig was ok i'd probably rebait after around 20mins.

When im float fishing i sometimes bring the rig in after about 5 minutes if i'd not had a proper bite as it usually means the little fish have sucked my maggots dry!

its swings and round abouts. If your not confident, rebait.

also the higher the stock in the lake the more often I would rebait, and vice versa. for example, on commercial fisheries, you are most likely to get a bite within 5 mins, and most of the time if you havent had a bite something is wrong.

but on places like hard carp waters with low stock density, the less disturbance and the longer your bait is in the water, generally, the better.