I think there's some merit to your argument, that there's some minimal level of understanding that's required before speaking becomes meaningful, but that your

I think there's some merit to your argument, that there's some minimal level of understanding that's required before speaking becomes meaningful, but that your time estimate is off by two orders of magnitude. Working in Sweden, where tech companies speak English internally, I've been able to follow the language learning journeys of quite a few people (including some using the strategy "don't bother"), and the people who end up the best speakers (with regard to accent, grammar and vocabulary) are invariably those who try to speak the language as much as possible as early as possible. Yes, they will have a strong accent in the beginning, but it goes away with time (though accents rarely disappear entirely). The native English speakers who've lived in the country for twenty years without speaking much Swedish daily still have strong accents.