Do you guys put in new tubes every time you replace the tires?

 

No. I carry one along in case things really go sideways though.

 

I try and have a spare set of tubes, just in case I screw up the install. But I've gotten pretty good at changing the tires. I'm still using the tubes the bike came with in my dirt wheels, they've been in 4 different set of tires. I will change them out next round just because they have close to 17000 miles on them.
I do clean the tube really well before reinstalling it. I've removed pine needles and little rocks from them that were definitely not there on the install!

 

Do you ever stop and wonder, "how in hell did this get in here!?!"

 

Riding at 10-12psi seems to help stuff get in there, I think. Happens to my bicycle tubes too, when I run low pressure.
I've had grass stuck between the tire and rim on a number of occasions.
As long as it's not flat I don't care how it got there.
But yes, I have scratched my head and had a good laugh about it.