Reagent grade is a specification, not a quality ranking. A technical grade solvent used for rinsing glassware is the correct choice for that job, and paying for HPLC grade there simply moves money away from the steps where purity genuinely changes your result.
Start from the detection limit of your method. If you are quantifying trace metals at parts per billion, the impurity profile of your reagent sets the floor of what you can see, and an ACS grade with a documented heavy-metals limit is the minimum. For a classroom titration reaching two significant figures, that same specification adds cost without adding information.
Read the certificate of analysis rather than the label. Two suppliers can both claim ACS grade while reporting very different residue-on-ignition values. The certificate tells you what was measured on the batch in your hand, which is the only number that belongs in your method validation.
Finally, write the grade into your standard operating procedure. When a substitution happens during a supply shortage, a documented grade makes the decision visible and reviewable instead of quietly changing your baseline.