I think this is an example of a situation where "if you need to ask strangers on the Internet about it, you probably shouldn't do it."
You are predictably going to find a range of opinions. None of them are crazy opinions and all of them will be supported by expert authorities and by examples of past behavior. It all comes down to the specific choice of endpoints in the time period, and belief in whether the behavior we are looking at is persistent.
If you look at small-cap value since about 2004, the answer will look like "no" even if you include the recent burst of good performance.
If you take the window back before 2000, to the first available small-cap value funds, circa 3/1993, shortly after Fama and French published their research, the answer will look like "yes."
If you take the window back to 1927, the beginning of the data Fama and French used, the answer will look like "yes-but." The "but" is that it wasn't really possible for a retail investor to invest systematically in small-cap value, the small-cap value effect wasn't generally known, there was no chance for widespread knowledge of the it to have any effect... and
you start to get into data quality questions and
questions of whether the market of in the early days was quantitatively the same
as it is today.
What we know for sure is that people with small-cap value tilt experienced perfection in 2000-2003, with small-cap value going up while the rest of the market has been doing down. But it failed to repeat that performance in 2008-2009 or in 2020. From 2004 through 2017 it really hasn't done much different from Total Stock--it plunged much farther in 2008-2009 but it had grown more before that.
But in 2018 it started to do quite poorly. And in 2020, when the stock market fell, it fell much farther.
So the people who added small-cap value after 2004 have been waiting up to seventeen years
for their ship to come in. Did it just come in? We don't know yet. Maybe? Or maybe it's just digging itself out of the hole it fell into?
Blue, small-cap value fund. Orange, total market fund.
So what that tells you is that in order to get the promised benefits of factor portfolios, you need to have the conviction to stay with them
for up to 17 years. And if you are doubtful enough that you need to be asking the basic question "should I," you probably don't have that depth of conviction.
So I will give you the standard Boglehead answer: just invest in a total market index fund, such as Vanguard's VTSAX or VTI or Fidelity's FSKAX or FZROX or Schwab's SWSTX or iShares ITOT, and be satisfied with getting the return of the stock market as a whole.