I was gonna say probably sound, until I saw the name John F Walvoord. Unless you are already of the 'Dispensational' persuasion, I would studiously avoid all eschatological topics.
Dispensationalism may be popular in the US, but it has no place in serious Bible study. Stick with the meat instead of the candy floss, and you'll be just fine.
Strangely, Dispensationalism is a 19thC English creation of a certain John Neslon Darby, founder of an exclusivist sect k/a Plymouth Brethren, aka Exclusive Brethren. Yep, 'exclusive' is even in their name, so in that sense they share something in common with almost all cults, but their theology was largely evangelical in nature despite that. At least until their leadership transferred to the US. The Brethren is now more or less a full-blown cult like any other, and JND would be turning in his grave if he could see how his 'baby' turned out.
But ironically, Dispensationalism made very little impact in its country of origin, even though you will find some adherents scattered here and there. The so-called 'Prophetic Witness Movement' is one such group that is largely Dispensational in outlook. How Dispensationalism became the dominant prophetic school in the US is one of the more bizarre stories in the history of the Church, and it is recounted in an excellent treatise by Joseph M Canfield:
For British readers:
.....and for US:
The British reviewer offers a succint & telling digest of the book.
Sorry, but I did not invent the terminology. It comes with the territory - namely, eschatology (= 'the last things').
Anybody who wants to understand what these terms mean can easily avail themselves of any good intro to the subject. I'll happily recommend a couple for anyone who is interested.