Wu

That is a reasonable exception and I should have said it. The advice is aimed at people who have not found their shoe yet, and for them a second identical pair is a bet on a shoe they have not tested over a season.

If you do buy a second pair, buy a different shoe, not the same one again. That is where most of the benefit is and people routinely buy a spare of what they have.

A sensible pairing for someone at your volume:

A daily trainer, cushioned, durable, unremarkable. Most of your running.

Something lighter and firmer for faster sessions, if you do any. Or a second daily trainer with a noticeably different feel if you do not.

A trail shoe instead, if some of your running is off road. That is a different purchase solving a different problem and it also gives you rotation for free.

What to avoid: two shoes with very similar geometry but different enough drop that you are switching between them without noticing. A large drop difference is worth introducing gradually rather than alternating from day one.

On how to rotate: alternate rather than running one until it is worn. Hard sessions in one, easy in the other, is the usual arrangement and it happens to give each pair recovery days automatically.

And keep the older pair in service after buying the new one rather than retiring it: that transition period is when you find out whether the new shoe suits you, while still having something known to run in.