The phrase 'is less extensive' is correct and usable in written English.
It can be used to compare two or more things with the implication that one has more of something than the other(s). For example: "The library's collection of classic literature is less extensive than the one at the neighboring university."
The thinking on gift cards is less extensive but has its place in that history.
But this time around, the battleground is less extensive, the battle-lines less clear.
"When past evidence is less extensive, differences in opinions do show up".
Glaciation is less extensive in the Alai and Trans-Alai mountains.
It is less extensive than many New England sites, but also has updates on grasses and wildflowers.
Compared with other major professional North American sports leagues, the N.H.L.'s revenue-sharing plan is less extensive.
"However, due to global warming, this landfast sea ice forms later in the year, attaches to the coast later, breaks up earlier, and is less extensive and thinner, subjecting Kivalina to greater coastal storm waves, storm surges and erosion.
In neither case is the result solely one of the two types, though 1 1 clay is predominant in the tropics after prolonged leaching and 2 1 clay more abundant when leaching is less extensive in more temperate climates.
The trade in Asian elephant ivory is less extensive, mainly because only some Asian elephants have tusks, and when present, they are far smaller than those wielded by their African cousins.
Research on Ella, approved in 2010, is less extensive, but the F.D.A., Dr. Blithe, and others say evidence increasingly suggests it does not derail implantation, citing, among other things, several studies in which women became pregnant when taking Ella after ovulating.
1Evidence on the impact of similar types of reforms introduced outside of the US, however, is less extensive (Finn and Gloster, 2010).
