A common rubric starts with descriptors for each expense account:   (1) Necessity,   (2) Reasonableness,   (3) Achievability,  (4) Sufficiency, and  (5) Optimality.   That is,  are we doing the necessary things, reasonable and suitable things, are the things (objectives) in fact even achievable  and are we committing sufficient resources to get to the objectives, and  and are we optimizing resources via economies of scale and other methods to ensure efficiency.

Then you can assign a risk-based scale to each account.  For instance,  our biggest expense, water/sewage, would top the scales in all these descriptors.  Analysis of the monthly water/sewage invoices quickly reveals that people are using more water, very likely because they are working from home.  The County is increasing rates has increased the rates in the last two years and has added a monthly base charge.  Accordingly, we have a rather good idea of what a sufficient budget would be for water/sewage.  Under-budgeting for water/sewage carries a high-risk of budget insufficiency, which would have effects in reserve accounts.

As far as any other maintenance, the HOA should take the view that no owner/resident should necessarily have to suffer through a component failure due to budget constraints.  We have the contingency fund for this very purpose.  The HOA should take all individual maintenance requests seriously,  be it moving a parking spot, installing new signage, replacing an inoperative light,  or a nest of aggressive stinging insects, as most things have some legal and fiduciary duty implications.

As for the reserve study analysis,  this document provides a good framework for understanding what goes into a reserve report and why.