When to lower a ceiling installed wshp for repairs?

[dicy]

Today I was working on a trane wshp, burned out compressor. I decided to replace the reversing valve at the same time just in case. Apparently I over heated the new reversing valve while brazing it as it is now stock in mid position.
This makes me wonder:
What do you replace when you have an electrical burn? I have heard of guys replacing the compressor, rev valve, driers and txv. Surely they won't do that in the ceiling?
When is it justified to lower a wshp from the ceiling to work on it?

[jeffflk]

We usually never lower them, what we will do it remove all the side panels to get really good access to them, and the top. The boss doesn't want to have to send 2 guys out when one can do the job, we just bust the rivots that hold it all in place and put screws in it's place. Good luck I hate those things