If you're using a 58 as a lob wedge, use a 54 as a sand wedge and for most of your pitching/chipping duties. Then carry a 50 when you have a lot of real estate on the green.

I would go for 54 degree as sand wedge. I use a 53 and 57 degree and most of my chipping if I have a lot of green to work with is either PW or 9 iron. I went for a series of lessons with a pro who specialises in short game skills. My score have improved and consistancy around the green has improved significatly. It is a lot simpler to chip with a PW and 9 iron than to controll distance with a lob or sand wedge. most amateurs chip short 90% of the time. they key is to simplify your shortgame, you will become more consistant and your scores will drop.

I've had a pretty lethal short game since 2006 and have gotten pretty good at controlling distance with pitch shots (I get quite a few one putt greens). Like I said, about 90 percent of my pitching and chipping is with the 54. The 54 has enough roll. I can play it back in my stance off a tight lie. From 25 yards in, I am also pretty deadly with the 60. I generally don't do full pitch shots with it because less effort is involved using a SW or GW. I also carry a 64 (discovered them in 2006).

Wedge selection is a very personalized thing. Your best bet is to find a Titleist Club fitter and have him/her do a wedge fitting for you. A lot goes into selecting the proper wedges and without being able to see your swing and technique it is almost impossible to tell you which wedge you should use. The combinations of loft and bounce along with your normal course conditions (hard/soft shallow/deep sand and the type of fairways and rough) coupled with your swing mechanics make wedge selection anything but trivial.

Find a good fitter that is a PGA professional and you will get the best possible wedges for your game!

Best of Luck

Since my last post, I have changed my Vokey setup. Still have the 54-11. Added a 58-12 and traded in my 60-07 and 64-07 for a 62-07. My other wedges are DCI 981 P and W (47 and 51). My two cents is that anything could be used as a "wedge" (I chipped under a tree from 100 yards with a 7 wood and landed the ball on the green). Those two way chipping irons (although rarely used) are capable of 120 yards or so with a full swing.