I would never recommend anyone use lime unless they have a pH meter, as the strips (even colorPhast) are just not accurate enough. Even with that, use safety precautions and err on the low side. I personally don't think any beer benefits from a mash pH of over 5.5, and even a beer with lots of roasted malts will be very easy to get above this with a strong base like lime.
I'm not willing to go quite that far. If you have the capability to dose your water accurately with lime, there is no more need to have a pH meter for that addition than with any other mineral addition.
If you are starting with a low alkalinity water like distilled or RO, then you know that you will need some alkalinity for highly acidic grists with significant crystal or roast content. If you have any confidence in the acidity correlations for various grain types, you can certainly have some confidence that you can calculate what the total acidity you are adding via your grist. With that knowledge, you can estimate what alkalinity your mash will need to produce an appropriate mash pH.
The great thing about lime is that you will get exactly the quantity of alkalinity in your water with respect to your dosing. And with that alkalinity being delivered in the hydroxl form, it is going to react with whatever proton donor it encounters. Its especially going to react with and neutralize those available acids (those sluts!).
So you can depend on this reaction to proceed fully to completion, unlike chalk. If you dose lime right and understand your mash acidity, the pH will be right. You don't have to worry about the buffering capacity like when you're adding acid to an alkaline water. Adding lime into an acidic solution is a straight one to one response when you are starting with little or no alkalinity in the water.
Nate, I have to disagree that 'in most cases alkalinity is a bad thing'. I've found just the opposite. I find that inappropriate alkalinity content is a bad thing. That goes both ways. Too low an alkalinity produces a thin, body-less beer that is likely to be tart. That might be a good thing in a Berliner Weisse, but not so good in other styles. Too high an alkalinity creates a litany of faults through excessive mash pH and wort pH. But the appropriate alkalinity produces a better beer every time.
There are brewers that brew beers like stouts using RO water and maybe some calcium mineral. They are making beer. But in the hundreds of darker beers that I've judged that have an acidic twang and thin body, I can only assume they were brewed with low alkalinity water. In some cases, I've been able to confirm from the brewer that they used low alkalinity water for the brew.
Conversely here in the land of very alkaline water, I've tasted some truly wonderful dark beers that I've queried the brewers as to their water adjustements. They typically do little to their water. (of course their lighter beers stink unless they've learned the magic of alkalinity reduction). Aiming for the appropriate alkalinity to coordinate with the needs of the grist is the path to better beer.
I have been advocating an elevated mash pH target for darker beers for probably 3 years now. I always found that if I over-neutralized my high alkalinity brewing water when I was in Tallahassee or my under-alkalinity RO water here in Carmel, my dark beers were sharp and unpleasant. Whereas, when the mash pH was a little bit high at 5.5 to 5.6, then those same beer recipes were much smoother. Recently, I was trolling through Kai's Braukaiser site and noted that he had pointed out a reference (I think it was either Kunze or Briggs) that said that a slightly higher mash pH helps improve the extraction of color and flavor from roast malts. That was an Ah Ha moment for me! It corroborated my empirical findings above.
That higher pH target also helps me understand why so many brewers using RO or distilled water have to reserve their roast grains from the main mash. That process helps moderate the problems of a too low mash and also allows the mash to naturally increase its pH as the mash progresses. That moves the pH closer to a range that the roast color and extraction is going to appreciate.
Appropriate alkalinity should always be a brewers goal, not 'no alkalinity'. That no alkalinity water recipe does not hold true for all beers. You can also fault Palmer's original nomograph and spreadsheet. It was the downfall of many a dark beer brewer since it recommends far too much alkalinity. But, don't go to the extreme in aiming for too little alkalinity.