The portals own listing search and that is not a winnable fight
Availability searches resolve to the major listing platforms, and a brokerage site competing there is spending against an outcome it cannot reach.
Anybody looking for space searches the portals, and the portals rank because that is their entire business. A brokerage listing page is competing with a platform holding every listing in the market.
Firms nonetheless spend effort optimizing individual listing pages, which produces a large volume of thin, expiring content on the site and very little traffic.
The listings still need to exist on your site, for the people who arrive by other routes and for the owners who want to see their property presented. They are not a search strategy.
Where the site can win is everything the portal does not do: why a submarket is moving, what a lease is actually trading at against asking, what a change of use involves, and what a specific kind of tenant needs.
The practical rule is to stop measuring listing pages by search performance and start measuring them by whether they serve the people you send to them. That is a different job and they are usually good at it.