Go read the continuous disclosure rules. Here's my take: The first price-sensitive announcement was deemed price sensitive by AVZ because it changed expectations regarding the size of the resource. The subsequent cores may be falling within the expected sizes as shown in previously published information - and therefore would not be considered price sensitive. Depending on the location and angle of M018DD007 319 metres may be neither more nor less than expected. Also, 319 may be the total core length, not the intercept length.
The operation of all four drills is considered "price sensitive" to certain hot copper folk, but not according to the ASX rules as far as I can see - because they are there, operating, just as it had already been announced they would be.
AVZ Price at posting:
25.5¢ Sentiment: Buy Disclosure: Held