I couldn't agree more, Chief, and if you think hard balsa is tough on blades, try using them on ebony, rosewood, and maple fretboards for inlay work!  Wow.  There's not really a feeling like that first cut with a new blade.  Ya wonder why you didn't change it sooner!

Why is a new build more worthy of a new blade than at any other time?
I ALWAYS keep a stone nearby whenever I am cutting balsa.
Your edge can never be too sharp.

Phooey Ty, that's bad advice! You just haven't lived until you build a model solely with a dull pocket knife. They just don't go as deep when you cut yourself. 

Before I revisited my aero model building hobby my son and I did a lot of deer hunting and I absolutely hate a dull blade

He turned me on to a company called Havalon that took surgical blades to a new level for boning and skinning and even fish filleting using disposable surgical style blades...very large form factor

I bought a few of the normal surgical handles (big fat ones for my arthritic hands) in two blade sizes and several 100 count boxes of their different surgical blades

I doubt I have used an Xacto blade more than 5 times in the last 7 builds

I think the prices for a handle and box of blades is real reasonable and they are very very sharp ...curious that they don't dull too badly with balsa but Monocoat does a job to the edge...(I think mostly a build of adhesive is making them drag)

PS look past the hunting stuff and look at the variety of handles and small form factor blades