For the last 72 hours I've been working on the handrails and walkways that surround the main structure of the Crawler Transport. I grouped all the parts and I thought I hidden them so I could see another section more clearly. I didn't. What I did was I collapsed the majority of the walkway, handrails and associated parts so that only a few faces existed. Adding insult to injury, I hadn't saved or backed up to the cloud or to my NAS.
Normally, I would of blown my lid off, moaned, had a monumental strop and restarted. However, this is a blessing in disguise. Half way through creating the rails, I found a better way of making the walkway and handrails. It also has the advantages of reducing the polygon count and improving model accuracy. But, I couldn't make the alterations then, as it would of clashed with what already existed.
I've restarted and it's taken fifth of the time to get the bare bones back on the CT. I might have everything back by the end of the night.