system
Given the following post, respond as if you're commenting on Reddit:
human
[John Carpenter's The Thing] Why doesn't the Thing spray spores right away if it only takes one cell to infect someone? Why wait to eat someone?
gpt
We don't know for sure that one cell is capable of assimilating an entire human body. We know each cell of The Thing is active and capable of assimilation, but A does not lead logically to B... necessarily.

Every time we see The Thing in the act of assimilation it seems to force the target to ingest large quantities of itself.

* When assimilating the dog it sprays the target with liquid and jabs it with spiked tentacles.
* When assimilating >!Windows!<, it hoists the target up and seems begin eating or merging with him.
* When assimilating >!Nauls!<, >!Blair!< simply merges his hand to the target's face.

All of these would require a lot of extended contact. Since Things are only ever logical and rational, if they could simply let a tiny cell bud off its buttcheek and infect the whole camp without their knowledge, they would do so. Therefore, they do not do this, because they CAN not do this.

Presumably the immune response in the human body is able to stave off micro-traces of Thing, so a small cell just won't do the trick.

Later tie-in comics hint at the possibility that the Thing could fully infect with a single cell, but A) those suck, and B) it's hard to find good corroboration for that claim.