That depends. Is it also more reliable?
If two books, one big one slim, prove the same thesis, what I would be interested in is the quality of the content, not the size. There can be a measure of efficiency in "have you really thought it through", but it is clearly complex - it requires measuring how solid the reasoning is.
Mind you, until the recent price cuts to Luna - Gemini 3.6 Flash wasn't even egregiously priced (but oh how things change in just 1 week).