When should I stop playing endless mode in Plants vs Zombies

plants-vs-zombies

I don't think there's already a clone question, if there is I apologize but I didn't find it.

It's kinda of a spoiler but not really a spoiler.

So I'm using this strategy and I have 142 flags:

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The thing is since flag #50 I'm not noticing changes in the behaviour of the AI. Basically I'm winning easy, I have just to restore the Pumpkin shield on the plants.
I really don't care about doing 1000 flags so should I expect some increase in difficulty or is that it?

The version is Game of the Year.

Best Answer

I've searched fairly extensively and I can't find anything that suggests it gets harder.