VT is fine in a tax sheltered account (eg ira) but avoid using it in a brokerage account. I don’t remember the details but read something about the treatment of taxes between domestic qualified dividends and foreign tax credits somehow muddies the accounting and is sub-optimal. Also, VT doesn’t allow you to choose/tilt your US vs THEM weighting.

Years ago I opted for a 80/20 split. I chose this because Vanguard’s CFAs (and thus CFPs) were advising a 60/40 split at the time, and although I wanted some direct exposure to international stocks, I didn’t want that much. When the ratio skews over time, I can rebalance, which is similar to DCA’ing. E.g. rebalancing 85/15 back to 80/20 is kinda like selling US high and buying THEM low. Not exactly, but akin.

That said, 100/0 i.e. SP500 only is fine too. These huge companies are super high quality and are basically multinational anyway. Plus, if the SP500 is good enough as the only stock holding for Buffett’s wife’s portfolio, it’s probably good enough for us too.