It depends on a number of factors - what is your feed in EC, medium, fertigation frequency, etc.
As a rule in coco I am happy if the EC runs higher than the feed, up to around 0.4 above feed in EC. Above that I get concerned, but usually just modify the fertigation frequency (irrigate longer than I am or increase events).
But I agree with what others have said about monitoring the plants for response - that is always key. I did see someone sharing a poster from new research suggestion a feed in EC of 4.0 was desirable during veg, which is double the EC I run even when pushing things. So it also in part depends on your feed solution mix also.
In general though - don't use one data point. Monitor run off over several events and assess.