You have to understand how a specific total stock market fund (VTSMX) will inexorably gain it's outperformance over very extended periods of time (again, decades, not years) and be comfortable with that (if you sell when it is temporarily out of favor and badly lagging lots of actively managed funds that can load up on hot sectors in any given market, you really defeat all of the intrinsic advantages of the correct total stock market index fund from a long-term shareholder friendly company such as Vanguard offers).
Choosing blindly and forget is more apt for choosing a hot actively managed fund that has done well over last 5 - 10 years and assume it will always be the same, particularly if that money manager uses a higher turnover, momentum type investing style (contrarian growth or deep value has higher likelihood of outperforming over time because they are buying when everyone else wants to give away temporarily out of favor stocks, and they are selling when market is getting frothy and momentum type investors are all too eager to buy those now in favor stocks that same momentum investors were quite willingly puking up 3 - 5 years ago).
I specifically recommend VTSMX, and not other low cost total stock market index funds, because it, in my opinion, is most likely to be shareholder friendly over the long-term (continuing to decrease expense ratio as total assets under management increase, automatically converting you to even lower cost Admiral shares when your investment reaches a certain point) and not doing something non-shareholder friendly for it's long-term investors like jacking expense ratio or changing the benchmarked index drastically some time in future (this is much more important in taxable account than tax-deferred account)
VTSMX is a great core investment, particularly in a taxable account, around which you can overweight or underweight other sectors over time with high quality, shareholder friendly actively managed, non-sector funds (true sector funds are, by mandate, stuck in a particular sector even if that sector is out of favor for many years and are a loser's game for truly long-term investors; I mean something such as Large Cap Growth / Value / Blend, Midcap same or Smallcap same) shareholder-friendly, actively managed funds.
When you get beyond 20 years, it is very hard for most actively managed fund to consistently overcome the at least 2 - 3% average annual return they give away because of high expense ratio, hidden transaction costs because of high portfolio strategy, and taxes.
And at this point, the relative perfomance chasing, asset gathering, actively managed fund which in reality has morphed into a quasi-index fund (they have so many billions of dollars under management that they can't take meaningful positions in any given stock, so they end up indexing vast majority of assets, and try and gain outperformance by overweighting in favor sector and underweighting currently out of favor sector). Problem is that type of strategy still has significant hidden transaction costs associated with it, and may not be as tax-friendly as you would like (VTSMX owns whole market, so capital gains distributions should be very low and tax-efficiency very high. Plus you are aggressive in proper sense - 99%+ in stocks at all times).
The fund managers who created a great record over last 5 - 10 years and drew in tons of hot, dumb money in process, has long since retired very, very wealthy, and leaves those choose blindly and forget investors with the crap, market lagging investment that that mutual fund has become.