Just looked at the two, seperate, hour-long sets we just did at Shrewsbury....
ten in the first set (late afternoon concert)...

and twelve in the second (on last thing at night,
so used some of our more uptempo material to make it more of a bop)...

No actual songs repeated, but two of our instrumental/jigs
were played in the first set, shortened and combined as a medley.

Used those two again (seperately, in their full form) in the second set as one is our 'usual' big finish number
- and those that follow us DO expect that one every time... Bless! ;0)

By way of reply to a couple more interesting points above...
We found a large number of of folk DID come to both shows
- but I had made a point at the first show that we would do a diff set of uptempo in the eve
- wonder if that made some minds up - hah! - either way! ;0)

And... consec songs in the same key...
we feel this makes little difference if/when we do just that...
this one in D might be 4/4 and uptempo, the next might be slow
and in threes - this one in Em might be in a ska/reggae feel,
the next in Em a fast rockier number.
Surely it's predominately the 'feel' of the song, it's own dynamics, pace, lyric etc
that gives the song individual character and to a large extent negates the fact that two might follow in the same key?
that makes the song varied.

All the best- Duncan