You can claim three specialties under your trade, and no more. It reads like a restriction. It is closer to the opposite.
What claiming everything actually does
If every plumber on the platform ticks all the plumbing specialties, then specialty stops separating anybody. The customer with a blocked stormwater drain sees the same list as the customer wanting a hot water system replaced, and the tradie who genuinely does stormwater every week is indistinguishable from the one who did it once in 2019.
At that point the only things left to rank on are distance and reputation, and the tradie who was actually the best fit for the job has lost the one factor that would have said so.
Specialty fit is the second-heaviest thing we rank on
Only distance counts for more. So the three you pick carry real weight — which is exactly why they cannot be a list of everything you have ever touched.
Pick the work you want more of
Not the work you are capable of. Most tradies can do considerably more than three things; the question the field is asking is narrower than that. Which three jobs do you want the phone to ring about?
You can change them whenever you like. They are a statement of what you are chasing this year, not a qualification.
A second specialty is worth points too
Claiming a second one adds to your profile score. A third does not add more — the score stops rewarding breadth quickly, for the same reason the cap exists at all.
What this protects you from
Other people doing it. A cap only works if it applies to everyone, and the value you get from it is not in your own three — it is in the fact that nobody can bury you by claiming forty.