Towcester is on today's card and the trap data here is worth understanding before you look at any individual runner.
Over 72 races in the database, the bias is one of the clearest you'll find across any UK track. Trap 3 wins 30.4% of races — 21 wins from 69 runs. Traps 1 and 2 sit at 20% and 18.1% respectively, roughly where you'd expect them. Then the numbers drop sharply: traps 4, 5 and 6 come in at 17.4%, 8.7% and 8.7%. Traps 5 and 6 are winning at barely half their expected share.
At most tracks, trap bias figures shift around within a few percentage points and the differences are noise. A 22-point gap between trap 3 (30.4%) and trap 5 (8.7%) over 69 runs each is not noise. That's a structural feature of the course.
The most likely explanation is bend geometry. At Towcester, trap 3 runners appear to take a position that lets them run a clean arc into the first turn — wide enough to avoid rail crowding, inside enough to not be caught wide all the way. The dogs in traps 5 and 6 are taking the outside line in a field that has already closed up, which means fighting for position through every bend rather than running a natural line.
None of this means a trap 6 dog can't win at Towcester — they do, roughly one time in eleven. But when you're comparing two dogs of similar ability and one is in trap 3 while the other draws 5 or 6, the Towcester data says the draw is a genuine factor. Worth checking before you commit.