Hi, does anyone know if it's possible to defer NS Release and wait 'til next release (all in one go)?

It is not

If you are in a high enough service tier, you can choose which of the four release waves you want to get the upgrade in as well (though you have to make the request well enough in advance), but there is no way to stay on an old version indefinitely.

For what it's worth, upgrades in NetSuite are fairly reliable.

No cloud-based service wants to maintain X number of old versions indefinitely (at least, not without being paid very dearly for it). That is part of living in a cloud-based service world. You have to accept the updates as they come. Take advantage of the Release Preview environment and UAT test anything you are concerned about, and file cases if you find bugs as soon as possible. If you find a major bug related to the new release during UAT, that will help your case in getting your update delayed, or getting your bug fixed as a priority before the release.

Thanks for the replies. We're currently short on resource that's why this thought came up as a worst case scenario.