The problem with all the LFS "chicanes" is that they are way too fast and wrongly shaped. One of the issues is the huge width of all tracks and other is the lack of tight turns. If we look at few of the corners individually we can defenately see a pattern.
Starting with Blackwood the T2/T3 is quite fast and the long straight really rewards any cutting done through the corners there. With the recent blackwood "fix" the curbs are far more friendly which make it even easier to cut the corners. The same really for both directions.
Problems: width, shape, cutting
Then there is the KY3 corner which has similar problems. Curb edges are bugged, the corner is way too fast and wide and you can gain time by cutting quite a lot. Really needs a redesign or at least a bugfix.
Problems: width, shape, bugged curb edges, cutting
Fernbay "chicanes" on the straights. Very fast and dangerous, getting the optimum line through these requires touching the tire stacks on both apexes. Easy to get wrong and cause a big accident to everyone coming after you. Curoiously enough the corners are placed on the middle of the straights so one might think that they are there to slow you down which they don't do at all.
Problems: width, shape, cutting, extremely dangerous
The other fern bay chicane-alikes. Always very fast, always going over the high curbs and mostly cutting as deep as it is possible to get away with. With the tire stacks the added danger of LFS-moonflights (R) is almost guaranteed.
Problems: again, width, shape, cutting, danger of autoX objects near the track.
AS5, the back straight kink. Probably meant to be another very fast couple of corners. The cutting is not such a big issue on this corner because dirt on tires will hurt corner exit altough there is some much green pavement on the insides of both turns allowing quite a bit curb on entry. The problems the huge width of Aston can cause have been quite succesfully taken care of by making the corner itself enough big.
Problems: too much green pavement
SO1/SO6. The "bus stop" is just a disaster waiting to happen. Again, too fast, too wide and one line through with walls right next to the track. Very dangerous set of corners.
Problems: shape, speed, lack of space, dangerous
Last corner of AS3. Quite nice corner which again is made too fast and the long straight really rewards cutting. The tire stack on the exit is one more accident waiting to happen as the fast line is to touch those tires slightly, setting them moving.
Problems: width, shape, cutting, autoX objects near the racing line.
The 2nd/3rd corners of KY3R. Another a bit strange set of corners where you can gain time by cutting the corner over full width of car.
Problems: cutting, shape, green pavement
Example of a chicane that just works. The AS5 turn 3, the 2nd of the slowest corners on that config. No rewards for cutting, slow enough and enjoyably challening on reverse config.
Always too fast and always too wide. And always the shape allows one quite straight line through. Make the corners slower, the road narrower or changing the shape to a kink or slow corner or anything else could make these a lot more interesting and fun to drive.