Hi Joe

 ​Some of the more seasoned members will likely give the true reason for the different sizes, However, I have noticed that generally, typewriters for home use tend to be 10 CPI where office units tend to lean more towards the 12 CPI. My reckoning is the 10 CPI is for ease of reading letters from friends and family, whereas 12 CPI is for getting more information per page on business letters. Just my thoughts.
  All the best
  Sky

I just picked up a 1950 sage green  RC Allen (Woodstock) standard model. It was Pica, so I "tested" it against the others that were Elite.  I definitely favor the Elite type.  I remember in typing class about the different sizes, just can't recall the reason.  If I find any "professional" opinion or fact in print or in person, I'll post here.

ztyper wrote:

From my experience, standards tend to have elite typefaces than pica typefaces. Currently in my collection, 6 out of 8 standards that I have (or 75%) are have elite typefaces. And the inverse is true with my portables: most of them tend to be pica than elite.

I agree that Pica is more common on portables, but I think for the standards, it might depend on the era. I mostly look at pre-1950's standards, and I find Pica seems to me more common on those. Just to double check, I looked just now at the first 50 standards I could find on eBay--which I must note is not a good indication of all typewriters, as eBay tends to have more older American standards--and 33 were pica and 17 elite. This is not scientific, but that seems to be about what I find when I am antiquing. Of my own collection, 2 out of 7 of my standards are elite, but the standards in my collection are of a similar demographic to the eBay sample--almost all pre-50's American brands. I used to think elite was more common on standards, until I had trouble finding certain standards in elite. I think on older typewriters, pica may have been more common--but I could be wrong.
 

I did a bit of research, and digging up period trade articles dating the teens, pre-teens, and twenties. It seems up to the twenties companies offered a variety of typefaces. In addition, standards for business forms, correspondence, and adaption of machines to existing tabulation and filing systems were also being thought out. An 1893 training booklet points out pica or elite was more of personal preference.  I remember the business correspondence I've seen was usually single spaced elite as the actual message area was limited by letterhead, perhaps a sidebar with addresses or phone numbers, salutations and closures. From about the twenties onward, the selections seemed standardized to Pica or Elite, particularly with the release of the Underwood No. 5. I  discovered there are conventions depending on the purpose and recipient of typed material. Rules for Federal Appellate Court attorney submissions, Screen Writers script standards, and Publisher/Editor manuscript submissions all specify that if typewritten they must be Pica type double spaced. This enhances readibility, and leaves room for comments, editing , and other notations; plus it aids in word count for the composing room if being published. Using the typwriter to fill out forms such as for machine maintenance or job applications, I found the Elite typeface the most useful for little boxes.  Someday I might get some insight from someone in "the trade"; but the history so far answers a lot of why.