No review tests everything. Each one represents a set of choices about where limited time was spent, and those choices shape the conclusion more than the product sometimes does.
Time is the binding constraint
Review periods are short and often overlap with other releases. Within that window a reviewer must set up, run tests, capture footage, write and edit, which leaves less testing time than expected.
Every test chosen displaces another. Running an exhaustive battery on one aspect means an entirely different aspect goes unexamined, and the review will not usually say which.
This is the main reason reviews of the same product disagree. They are frequently not contradicting each other so much as reporting different subsets of the same object.
Tests are selected by expected discrimination
Experienced reviewers prioritise tests likely to reveal a difference. Measuring something that performs identically across an entire product class produces a number that informs nobody.
Attention therefore concentrates where products vary, which is why coverage of a category narrows over time as the shared elements become uninteresting.
The risk is that a genuine regression in a settled area goes unnoticed, precisely because everyone stopped checking the thing that had not changed for years.
Repeatability limits what can be claimed
A measurement that cannot be reproduced under controlled conditions cannot support a firm statement. Anything dependent on ambient conditions, sample variation or network state is fragile.
Reviewers handle this by repeating tests and reporting typical rather than best results, which is why quoted figures often sit below what the same equipment can achieve once.
Subjective assessments are treated differently again, usually as impressions rather than findings, because a single reviewer's experience is a sample of one.
Sample variation is rarely visible
A review generally covers one unit. Manufacturing tolerance means that unit may sit anywhere within a distribution, and a single sample cannot distinguish a pattern from an outlier.
This is why reviewers are cautious about declaring a defect from one example, and why patterns reported by many owners after release sometimes contradict a favourable early review.
What the omissions tell you
A review that does not mention an aspect you care about has usually not tested it, rather than found it unremarkable, and the two are easy to confuse.
The most useful reviews state their method and their gaps plainly, because a reader who knows what was not examined can seek that elsewhere instead of assuming it was fine.