Having two irons for doing a broad range of work with an old Stanley plane is very common. One iron for heavy work, and one for medium to fine work. In fact, it is one of the recommendations I give to beginners, or those getting into hand tools for the first time, because they can save money and still get stuff done. That is exactly what I do, however, the irons I choose are the real secret.
I generally like to keep and use the original thinner blades. There is nothing wrong with them and their thinness can be an advantage. The second blade I use is one from Veritas (usually O-1 steel), but you could also use a Hock blade in the same way (they're both ~3/32" thick). The point is that it is thicker than the original blade.
In the picture above you see two blades, one with camber, and one without. The cambered blade is the thinner original and it has an 8" radius curve for mass stock removal. This is important if you thickness by hand, or need to do some quick one side flattening of a board to put it through your thickness planer.
The new thick blade is sharpened relatively flat, with just the corners relieved, and can be used for general work, or smoothing.
So, why two blades of different thicknesses? Answer: Because now I don't have to move the d@mn frog ever again. Yeah, I still have to turn the screw for the lever cap, but that just take two fingers. The best part is the range of work that can now be done.
I know I didn't invent this, but I don't hear it spoken of very often in this way. Give it a shot and see what you think, might just save you some money and time on another plane.