Runoff elections for president if 270+ EV aren't won with >50% of the vote?

[Skill and Chance]

In recent history, these elections would be impacted:

2016: Almost Safe Clinton- a ton of anti-Trump 3rd party voters would be scared straight by how close it actually was, also turnout dynamics would shift in favor of Dems

2000: Lean Bush?- this one is complicated, because all the legal disputes over Florida don't happen as neither candidate is within a recount of winning the EC in the 1st round.  The general expectation going in was that Bush was favored and would probably win the PV, but he was hit with an October/November surprise.  In this scenario, he has more time and distance to explain away the DUI and get the campaign back on a different issue, particularly assuming there would be a runoff debate.  Bush/Republicans also acted rather overconfident, campaigning in CA, etc.  On the other hand, Nader- if Gore picks up nearly all of the Nader vote, he wins.  I certainly think WA/OR/ME/MN/WI runoffs would favor Gore by wider margins.

1996- Almost Safe Clinton- the runoffs would generally be in states where Clinton was at 47-49 and Dole was at 39-41.

1992- Toss Up, determined by which candidate Perot endorses

1980 (deciding state was <50% even though PV was >50%)- Almost Safe Reagan, the opposite of 1996

1976 (deciding state was <50% even though PV was >50%)- Lean Ford, he was gaining dramatically  in the polls in the final month

1968- Lean Humphrey?- he was gaining late and there actually are enough Northern/Western states under 50% to offset Wallace endorsing Nixon and giving him all the Southern runoffs

1960- the deciding state, Texas, was >50%, even though the PV was <50%, so Kennedy still wins in the 1st round

Earlier elections:

1948- Likely Dewey- this was a last minute surprise much like 2016 that caught the candidate with a presumptive lead off-guard.  I think Dewey would be able to rally back and R turnout would increase.

1916- Lean Hughes?- similar situation to 1948 IMO

1912- Likely Teddy Roosevelt- IMO most R's would take him as the lesser of 2 evils, the parties could be very, very different today

Thoughts?