It’s not a question of judgement or applying any kind of ”rationale” to “push on a bit”. Mutt and 763 Jock have explained the rules. The trip is planned on the ground, pre-flight, using still air and typical single-engined speeds for the aircraft type. It is accepted by the operators and the regulatory authorities that if an engine failure happens at the furthest distance between two suitable airfields, the reality is that there probably will be a wind component and the aircraft’s cruise speed may be a bit different from the one used at the planning stage. So if 60, 120, 180 or 207 minutes are exceeded, no rules have been broken and nothing is less safe.