But yeah, given the right conditions, if you're planning to go for SoZ, you would have monopolised ivory one way or another early on to ensure you don't get beaten to it.
Wasn't possible here, because there were 3 clumps of Ivory on our continent (Large map): I got one, the second was some way south of the Persepolean Mountains and (temporarily) colonised by the Zulus/Dutch (until I stole it from both of them!), but the third was deep in Summie territory, a long way behind their nearest border.
And picking a fight with an opponent that you do not have a solid plan for and certain odds of beating would also be considered sub-optimal.
Well, I did have a plan: I 'only' had to take 3 Summie towns, including the Horse-town (which was also a chokepoint), to get those Horses, and then I could have thrown every unit I owned in there, so forcing Gil to come by sea on his next attack.
After beating on the Zulus, I did have a fairly decent GA-built Immortal-stack (and more coming), and Cats + Pikes to go with it, so that didn't seem impossible. And in my defence, most of my "early" wars at Emp are (necessarily) declared from a position of weakness.
Where I went wrong was pushing forwards too early and — as it turned out — just as the Summies got Chivalry
So while I was expecting my A=4 Immortals to face D=3 Pikes in the towns, I
didn't reckon on facing them in the field as well — but by that point it was too late to back down ("The Sumerians refused to receive our envoy!"), before I'd taken my beating.
I'm not as patient as you were and would have quit once I wasted hammers on SoZ. That's just difficult to recover from on Emperor and above.
I can't remember exactly, but I think I turned those shields into my FP instead (also 200 shields). So it wasn't a complete waste.
I usually only quit/restart when it's clear that a game has become unwinnable (like, my Spears are getting mown down by Cavs/Tanks!).
Although I must admit that I felt like quitting when Persepolis fell, my Palace didn't move very far (and also not to my FP-city, thankfully!). And Gil also apparently thought that loss meant he could afford to be magnanimous in victory, and signed a peace treaty shortly afterwards. His mistake: my proud Persian folk hold grudges, and have long memories...