Saints planned to interview Mike McCarthy; McCarthy didn’t garner enough interest from Saints and will take a year off

Everything has advantages and disadvantages. The advantage of what you propose is that you don't use up much future salary cap on players no longer under contract or you can more quickly move on from players without taking a big cap hit.

The disadvantage is that you use up more of the current cap on signing new players to bigger contracts, because you use up more of the current cap with each signing. That would mean signing less marquee free agents.

A lot of the same fans that complain about the cap management also start complaining about the Saints not signing enough big name free agents fast enough, the very minute free agency starts.
I think a healthy dose of both can be fine. If we were starting the year $15m over the cap and could give reasonable extensions or bonuses to our best young or most promising players to get under the cap I wouldn't have an issue with it. But we're not doing that. We're adding void years to players that are in decline or not even worth their contracts to pay for past mistakes and misses.

As someone else pointed out earlier (sorry I don't remember who), we should only be using that strategy to keep our own good young players when we're close to competing, not to sign free agents while we're in the bottom half of the league.