This’s what the 2023 Mazda CX-5 owner’s manual says:
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Based on mostly highway driving by the OP, it’s hard to be qualified as “severe driving conditions”. The best is to follow Mazda’s recommendation and use “Flexible” OCI which can be used in normal and severe driving conditions. And the maximum OCI by “Flexible” is 12 months or 7,500 miles.
IMO any current synthetic oils can handle 7,500 miles of service under most driving conditions. There’re too many UOA reports can support that. Considering Toyota has been using 10,000-mile OCI under any driving conditions with a super-thin 0W-16 oil for many years you should feel Mazda’s oil change interval at 7,500 miles is pretty conservative.