Some lessons learned in building big prim objects

The basilica prim object has 1,390 prims. I grouped the prims into the parts of the basilica. Facade, dome, nave, aisle, etc. Unfortunately I found out that I was short on sim space at the back and I have to move the entire basilica forward.

My immediate reaction was to link the entire basilica into one object and move it by hand. That worked, but when I have to edit it I could unlink individual prims probably because of nested children. So I unlinked it all again. It took a very long time and resulted in the entire basilica exploding, with 1,390 parts strewn all over the place.  I was shocked.

Fortunately I have an oar back up and reloaded from the previous edit. Here are some of the lessons I've learned (which are probably obvious to professional builder).

1. Always backup with an oar or iar.
2. Don't link big builds into one object, it will take forever to copy into the inventory.
3. When moving parts of a big build use build math. That is use + or - the value on the build input boxes rather than manually moving parts. It's a precise way to move stuff around.
4. Use a test prim when using build math. Test first how much value is needed to move norht, south, etc.
5. Use prims as a ruler to measure stuff. You can divide it by build math / to get equal parts.
6. After using build math always select another prim to deselect the edited object. I frequently want to move my avatar to another place, forgetting that when I press the up/down arrow keys the value in the build menu goes up and down instead of the avatar moving.
7. Frequent editing mistakes are forgetting to enable/disable stretch both sides, and edit link parts.

Measuring prim for the basilica's bell tower. The cork screw sculpty are stairs.