I have an older Cervelo P2C with Dura Ace 7800 10 speed components on it.

I've race 40K TTs, but not so much the last few years.

I usually leave 39/53 with a 12-23 cassette on it. TTs are usually on level ground, so that works just fine.

I take it out and ride it every month or so just to see how fast I can still go.

If I needed to go uphill, I'd put on an an 11-25 or 12-25.

I also have a set of 42/54 rings for it, but lack manliness to push that anymore.

I can't easily run a compact crank because the FD hangar is old style and only goes down to about a 52 large chain ring. I don't care, if I need a smaller big ring for a TT, I'll just get one of these -> https://www.electricbike.com/gruber-assist/