The case for nearshore work is usually argued on cost and usually decided on something else. A day rate is a number in a spreadsheet; the thing that actually determines whether an engagement works is how often a decision has to wait until tomorrow, and that never appears in the quote.
This guide is written from the supplier side, which you should factor in. We are a consultancy in Warsaw working with clients across the European Union, so we have an obvious interest in you concluding that this model works. What follows therefore includes the cases where it does not, because a guide that only argues one way is an advertisement with chapters.
If the work needs constant informal contact with people in one room, no amount of time-zone overlap fixes it. Distance is a constraint on tacit knowledge, not on hours.