Words such as all, some and none determine how strong a logical claim is. Replacing one with another can turn a valid conclusion into an unsupported one.
Some means at least one
In standard logic, some red counters are round means at least one counter is both red and round. It does not mean most red counters are round. It also does not, by itself, mean some red counters are not round.
Every red counter could be round and the some statement would still be true. Everyday conversation sometimes suggests a contrast, but a formal puzzle should be read according to its stated logical conventions.
None excludes overlap
No red counters are square means the red and square groups do not overlap. This also establishes that no square counters are red. Exclusion is symmetric in this way.
By contrast, all red counters are round does not establish that all round counters are red. Inclusion has a direction; exclusion between two groups does not.
Exactly changes the task
At least two and exactly two are different constraints. With at least two, three qualifying objects are allowed. With exactly two, a third would violate the statement.
In a counting or arrangement puzzle, identify these words before testing candidate answers. A solution can satisfy the broad idea of a clue while violating its exact quantity.
Try an original example
Some striped tiles are green. No green tiles are cracked. What follows?
At least some striped tiles are not cracked: the striped tiles known to be green cannot be cracked. It does not follow that every striped tile is intact, because striped tiles outside the green group are unconstrained.
Check the minimum guaranteed claim
Ask what is true in every allowed arrangement, including arrangements with the smallest possible overlap. This prevents upgrading some to all or possible to certain. When a conclusion feels obvious, look for the exact quantifier that supports it.