Adobe Illustrator is pretty frustrating to use in terms of sizing and positioning letters in terms of capital heights, like 1" tall letters. Adobe Illustrator is not geared for this. It only sizes type according to the size of the invisible em square, not the capital height of the letters. Very often the only recourse a designer has is converting the type to outlines and doing a little math to numerically scale the letters to the desired size.
Adobe Illustrator wasn't specifically designed for sign making use, and its team of developers have done very little at all to accommodate specific needs of sign designers. Adobe Illustrator was made for print related design where people spec type in points & picas and use a layout grid where the em square is right at home.
CorelDRAW is slightly easier to deal with than Adobe Illustrator in terms of making a 1" tall letter actually 1" tall. Unfortunately, it only works with blocky typefaces, like Helvetica. You can type a letter "H" or "E", size it to 1" tall and it will work. It's a lot more hit and miss with typefaces whose characters pass slightly (or a lot) below the baseline and rise above the cap height line.
Sign making applications like Flexi size letters based on the capital letter height, not the em square. All fonts have built in data setting a base line and cap height line. This is what Flexi uses to make a 1" letter actually 1" tall as well as allow users to set line spacing to specific distances like 1/2" between lines of lettering.
I've made repeated requests to Adobe to offer an optional letter sizing mode where cap heights are set in units of inches, centimeters or even specific pixel heights (this would be great for web design). They haven't seemed to listen. I think it's going to take more requests from other people to make something like this happen. I'd write a plug in for Illustrator if I could, but I'm not a programmer.