Inherent vs Residual Risk

1. Considering the initial risk assessment is done taking into account controls already in-place, is it accurate to say that if these controls are sufficient, there should be no change between the inherent and residual risk score?

Your understanding is correct. If the assessed risk, considering controls already in-place, are considered acceptable according to your defined criteria, then assessed risk and residual risk are the same.

2. Added to which, are there any circumstances where you would risk assess assuming NO controls?  You wouldn't approach a risk assessment for crossing the road with worst-case scenario at the outset, i.e. with a blindfold, earplugs and at rush-hour there is a high probability you will be killed?! That can't be your starting point or all risk assessments would be artificially skewed.

An example of a circumstance where you would assess a risk, assuming NO controls applied, is to identify the full impact of the risk occurring, so you can evaluate whether the effort and cost of applied controls are worthy.

This article will provide you further explanation about risk assessment:
- ISO 27001 risk assessment & treatment – 6 basic steps https://advisera.com/27001academy/knowledgebase/iso-27001-risk-assessment-treatment-6-basic-steps/

These materials will also help you regarding risk assessment:
- The basics of risk assessment and treatment according to ISO 27001 [free webinar] https://advisera.com/27001academy/webinar/basics-risk-assessment-treatment-according-iso-27001-free-webinar-demand/
- Book ISO 27001 Risk Management in Plain English https://advisera.com/books/iso-27001-annex-controls-plain-english/