one check
Your time zone, checked properly
Most tools compare the zone's name against your address and stop there. That misses the case that actually shows up: a zone set from outside carries the right name and the wrong rule.
What this one page cannot tell you
Whether your time zone matches where your connection comes from. That comparison needs your address, and it lives on the full check. A mismatch there is an indication and never a proof: emigrants, commuters and anyone travelling produce it honestly.
The interesting part is usually not a single value but the disagreement between two. The full check reads all five layers and shows you where they contradict each other.