Hi Dale,
I prefer to work in original composition. When the composition become bigger/complicated, you can just PreCompose it. The disadvantage of render and continue on the next comp are :
i. Harder to trace your workflow after few round or days/month.
ii. Might have quality drop issue if mov is render in lower video format setting and you continue to render it again and again.
iii. Don’t have option for scalling without losing the quality especially for gfx element created using illustrator/AE.
Just my opinion.. 🙂
Regards,
AESheriff
https://aftereffectbasic.blogspot.com/