I have seen this verse used to argue for sanctification…

I have seen this verse used to argue for sanctification as a one time experience subsequent to salvation:

I Thessalonians 4
3 For this is the will of God, your sanctification: that you should abstain from sexual immorality;

If ‘sanctification’ here refers to a one-time experience of sanctification that happens after one gets saved, wouldn’t that imply that it is normal for Christians who are saved, but not sanctified, to engage in fornication?

Is sanctification as a one-time experience after salvation a helpful way of interpreting this verse? Doesn’t it make more sense to see sanctification as something that all believers need to walk in?