To me, if it can't burn multi-session CDs/DVDs then it's not *proper* burning software. I regularly backup my photos or new versions of software onto multi-session DVDs. There is only Nero that I find does a reliable job of this.
I found that I only used multisession discs about 10 years ago - I then found out how unreliable multisession is....the hard way.
These days if I seriously wanted have the kind of chop'n'change
facility that multisession gives you, I wouldn't consider using anything other than DVD-RAM discs. They're specifically designed for this kind of use and are natively supported by XP and above, (they just appear as a removable HD to the system).
DVD-RAM has write-cycles in the vicinity of 100000 times, (compared to 1000 for CD/DVD-+RW), extremely efficient error recovery and it verifies as it writes in hardware, (although this can be bypassed to speed up writing). Sure the discs cost a bit more but you get the benefit of increased data security.
And considering you can get drives that read/write them for AU$30 it's a no-brainer.
But I find a flashdrive so much easier
Amazes me in some of these "which is best " threads that people recommend ImgBurn or ConvertXtoDVD. ImgBurn is fantastic at what it does, burning image files like ISO's. ConvertXtoDVD is fantastic at converting movie files to DVD format and burning them for you.
NEITHER of them can burn a multi-session data CD/DVD.
It's usually because the original poster didn't give enough info on what they wanted it for.