The vast majority of SSB stations are within +- 3kc from center. A fair share of the SSB stations is locked and most manufactures do at least a ballpark tweak at centering. With that said, there was a time before PLL’s hit the market that I wanted more clarifier coverage because many stations were far off frequency. We didn't have any locked clarifiers back in the early days of SSB CB's. For a CB radio, I still want all my clarifiers unlocked, but less is more concerning stability and ease of tuning. It becomes a choice between missing an occasional station that’s transmitting beyond the tighter tolerance or possibly sacrificing stability and tuning ease. Remember the wider the clarifiers spread, the more difficult it becomes to return to some semblance of true center. The closer you can get to true center is exactly what you want while monitoring. IMO if you’re really into SSB and want more spread, purchase a ham radio instead. Meanwhile you won’t miss much with a narrower stock spread.