How often do you replace a chain?

So, the chain on my fixed gear bike (48x16) is at a super awkward length, where removing one link would bring the back wheel to about 1.5mm from the seat tube, but leaving it at its current length, the axle is right at the back of the (horizontal) dropout. Removing the quick link would probably get it to the right length, but I am hesitant to re-use a pin from the chain to re-join it. Can you buy 1/8 inch chain pins for this purpose, or do people just re-use a pin from the chain?

Nevermind, Condor sells 1/8" pins: https://www.condorcycles.com/collections/chains/products/ybn-qfd918-single-speed-connecting-link

Apologies if I've misunderstood you, but have you overlooked the fact that you need to join outer plates to inner plates.

If you remove the quick link, you'll also need to remove an inner link to be able to rejoin the chain: ie links have to be removed in pairs (inner and outer).

It does depend on your chain breaker how easy it is, but you can partially push the pin out so the inner link is freed, but the pin is still held by the outer plate.

Then take out a link pair from the other end of the chain, flip the chain over and rejoin by pushing the pin back in.

This is how it was done BITD before quick links and is safe, you just need to make sure the pin protrudes from either side an equal amount.

Yeah, I guess it would shorten the chain by the same amount... Maybe a half-link is what I need then.

I had a bad experience re-using a pin on my road bike in the past (chain snapped, resulting in a bad crash) and only use solid replacement pins now as a result. I'm sure it's possible to re-use them safely, but I'm not taking the risk again.

I've only had a joint I made split once but never had a split/missing/quick link break so they are now my preference.

Easier too.

I've ordered a KMC half-link. Hopefully it plays nicely with my Izumi chain :/