Updating frequency for a software is related to two main factors:
[li]The addition of new features
Most of times, a software updated very often is because of bugfixes. A software with very frequent updates often is because is buggy and needs frequent bugfixes.
ImgBurn is constantly updated, but not on daily basis, because it is thoroughly tested, so there are very few bugs left after it is released.
btw, latest version has been released recently (on February the 10th)