In my experience a chub pull is slow and steady . A barbel line bite is fast and aggressive . Almost like you are getting a 3 foot twitch but the rod does not continue in to an ark with a fish connected ...
Interesting
My experience is different
What we call a chub ‘ thwack’ tend to leave the rod end rattling and my assumption is the chub attacking the bait , smash and grab style , feels resistance and releases the bait
If I get tremors or gentle pulls I assume the position and assume it will develop into a barbel bite
Not always but develops more times than it doesn’t
Re OP - absolutely no hard and fast rules
Some days a super short hooklink works if fishing with a big PVA bag
Other times if I’m into a shoal of fish and the bites dry up I always lengthen the hookink especially if maggot / caster fishing
Often the fish will move up in the water and intercept the feed - a longer hooklength allows the bait to cover more of the water it drops through the column and I have lots of barbel take on the drop albeit more a summer occurrence
Also better fish often hang back off the main shoal although that can be countered by just dropping downstream a few feet but if they are wary a decent distance between feeder , mainline and bait never does any harm with wiser fish
Completely agree re too many anglers default to heavy leads
Again when I fish ‘ barbel alley’ on our fishery and have been hemmed in a peg I’ve lost count of the sessions where a delicate little 30g feeder completely outfishes the lads pounding their swims with 3 & 4 oz leads/ feeders often replicating a great naval battle
Assumption is they prefer the ‘ sanctuary’ of my peg and a little occasional plop along with a small amount of freebies is quite natural and had some brilliant days whilst the guys either side of me are blaming otters, poachers, cormorants etc…for their lack of fish
