Euphorbia millii

Yo, experts!
I just bought an (expensive!!!) Euphorbia millii at my local nursery. The salesperson said to hardly ever water it. Too much water and it will get rot. I was very surprised, so I need your wisdom. Of course I wouldn't water it often, but "hardly ever"?
Here's a quote from one of the relevant Web sites:
"Euphorbia hybrids are truly tough plants and can take just about anything including relatively dry or overly wet conditions, temperatures between 4 and 40+ deg C, part shade to full sun and a variety of growing media. However, to give of their best they do require moderation in all the above (they can survive lousy conditions but don't enjoy them!)."
This sings an entirely different tune.
So whom should I believe?
Anybody on NG has real-world experience or educated opinion about this plant?
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