She's had Vogue China and Vogue Germany cover (not the blue chip Vogues but still more than some models from her time have. Plus she is a regular in Vogue US and has been featured in Vogue Italia and Vogue Paris etc... she's certainly not a stranger to Vogue, but that's kind of off topic
One of the times she skipped Milan was due to personal reasons, I'm not 100% sure what the second time was in regards to the 'big opportunity', things don't always work out as planned. Who knows. Plus this time she seemed very intent on Milan if her twitter was anything to go by, and actually seemed really excited about it, and disappointed that she was going to miss it. She has done very well in Milan in the past, some people in this thread believe it is her best city...
Sure I may be bias, but I just trust that she's making the right decision.