Call me a unicorn because I do exactly that. 2016 for example, third party for president, Republican for senate, democratic for congress. That's just on the federal level. 2018 we didn't have a senate race, but I voted Democratic for congress and Republican for governor and Lt. Governor.
What I see from studies of independents is you have approximately 40% who lean Republican and another 40% who lean Democratic. Now those numbers vary, go up and down. What's important is unlike those who call themselves Republicans and Democrats who will vote for their party's candidates 90% of the time. Independents who lean toward one party or the other will vote for the candidates of the party they lean toward 70%. Again this varies from election to election, going up and down, but on average it is 70%.
That leaves just 20% of independents with no leans, what I call true or pure independents. This is between 8-15% of the total electorate. This is also why or it is these true or pure independents why independents as a whole can vote for Democratic congressional candidates 57-39 over Republican congressional candidates in 2006, then reverse course and vote for Republican congressional candidate four years later in 2010 by a 56-37 margin. In 2014 independents voted for Republican congressional candidates 54-42 over Democrats, then in 2018 voted for Democratic congressional candidates by the same 54-42 margin.
If you want to look at the presidential races, 2000 independents went to Bush 48-46, in 2004 for Bush again 48-47, for Obama in 2008 52-44 over McCain, but switched to Romney in 2012 51-48 and for Trump in 2016 46-42 over Hillary. with 12% voting third party against both Trump and Hillary. You could take this back to 1996 when 50% of independents voted for Bill Clinton, 33% for Dole and 17% for Perot. In 1992 it was 43% for Bill Clinton, 28% Bush and 30% for Perot.Independents are much more apt to vote third party than the party faithful as seen in 2016 with 12% of independents voting third party compared to just 3% of Democrats and 4% of Republicans.
You don't see the wild swings in presidential election as you do in congressional elections. Usually wild swings among independents such as the 57% voting Democratic in 2006 falling to 37% in 2010, a drop of 20 points is caused by anger at the party in power more than who the candidates are. The party in power did something independents didn't like or passed something they didn't want and they took their revenge by switching their allegiance form the party they once voted for to the other party. In plain English, they became very unhappy campers and wanted revenge.
It's high past time that we start electing Americans to congress and the presidency who put America first instead of their political party. For way too long we have been electing Republicans and Democrats who happen to be Americans instead of Americans who happen to be Republicans and Democrats.