In general, a prohibition period can extend beyond another sentence because sometimes it's only a prohibition that's imposed. Where they exist in other circumstances, we have other provisions in the code that prohibit convicted child sex offenders from being around playgrounds, from being anywhere near children, all those sorts of things.
We have recognizance under section 810. Those orders, in the variety of circumstances that they can be imposed, can be for particular lengths of time even though a person may spend much less of a period of time under a probation order, or in custody, or whatever the other part of the sentence is. It can extend a particular number of years.
With respect to your question regarding varying up or varying down, what was contemplated here was a varying in the terms of conditions prescribed, so it could be that the scope of the prohibition is changed. I would suggest that if the period were extended, then offenders may well be seeking a judicial review of that extension if they thought that was extending their sentence beyond what was originally contemplated.
This was drafted to permit the person to come back before the court and say, “I can't comply with that anymore because of the following circumstances”, so that the individual wouldn't then be in breach. There could be some variation, or because of some change in their behaviour, some steps they'd made, or some desire on their part to engage in some occupation that might put them in violation of this, so they'd be able to do so without running afoul of the prohibition order.