Thirtyfive years ago, when buying checks through one's bank was the sole option, if you got a "business" account with a bank, you had to buy "business" checks. One difference between a "business" account and a personal account was that on the business account, the incorporated or unincorporated company (say Simply Wonderful Apps) had the option of changing from John Doe to Richard Roe as the Treasurer of Simply Wonderful Apps
and the person signing the checks, whereas a personal account in John Doe's name could not be changed to allow Richard Roe signature authority over the account. For a self-employed person doing business as Simply Wonderful Apps, a personal checking account would do just as well,
since the need to change the person responsible for signing checks might never arise. It was, of course, important to have a separate checking account for the business because it made book-keeping simpler and also separated business expenses deductible on Schedule C from personal expenses. But it was not necessary to have a business account or business checks to run a small business.
In addition to the various advantages described in other answers, one advantage that I found for larger checks is that various money management programs could do things like
print an address below the name on (computer-printable) checks so that after folding,
the check could be put into a window envelope and mailed directly. For the one
check to a page format, the programs could print additional information on the
blank area below the check (e.g. explanations about the check, company logo etc.
So, it was convenient if one had to write several checks each month. But if
outgoing checks are infrequent and extra security is not much of an issue, there
is less reason to spend a lot extra on
business style checks rather than the personal style checks.