Reply to 30 songs?! Thats enough for like 3 sets?!

Heard this the other evening when going to my friends place to play some tunes.

Scenario detail: My buddy calls me out of the blue to play some tunes at his place. About 10-15 people, 4 or 5 of them local DJs, others being some promoters and some being regular club goers.

Loaded my USB with about 30 or 40 tunes, mostly new stuff I downloaded, a couple accapellas, etc. One of the local DJs was already playing some tunes when I got there and my buddy told me I could play next if I wanted to.

Plan was to switch every 4 or 5 tunes. I make my way behind our makeshift booth to the Technics, plug in my USB and it starts to load up my songs.

Some other background info: Guy before me wouldn't call himself new, but hes been playing tunes for about 2 years, but doesn't own any gear . Type of guy that likes to only buy off the front page of Beatport and any tune over a year old is considered "old school". Ive been playing for about 10 years, but its only been the last 2 years I switched to digital format.

He sees me coming over, makes some room and lets me plug in. He takes one look at the song list from the USB and starts freaking out.

Takes off his headphones and starts yelling for my buddy, wondering why I am going to play such a long set. I explain to him that we're switching every 4 or 5 tunes and that I probably wasnt going to play all of em, just wanted to have enough for any scenario.

He scrolls through the songs and asks me why I carry so much music, which prompted the thread title : "30 songs?! Thats enough for like.... 3 sets?!"

The rest of the evening was fun, just some beers, talking shop with other DJs, talking about DJ Shadow lol, and trade songs.

At the end of the evening , the DJ before me says I played well, but should be considerate when playing with other DJs, as its rude to assume you can play for more than 1/2 an hour.

I brush him off, but as im driving back, I start believeing about todays DJs and how 1/2 hour sets are starting to become the norm, hour long sets are frightening to most and 2 hours is an eternity to most everyone except the older guys. I prefer to play at least 2 hours but to each his own

What do you guys believe? Do 30 songs = 3 sets or one?