How the Tablets were written - all at once or letter by letter?

Question

In my previous question the Torah says explicitly that the Tablets were written by G-d's finger.

Does it mean they were written letter by letter, as one finger can do, or all at once?

Answer 1

This is how Or HaChaim sees it (here):

"כתובים באצבע אלהים": והודיע הכתוב אופן כתיבת הלוחות במה נכתבו ואמר כתובים באצבע אלהים.
פירוש כי היה ה' מצייר צורת האות באצבעו כביכול.
פירוש בחינת אור אחד מאורו יתברך בדמות אצבע כנגד הלוח כשיעור שטח אברי האותיות כדי שלא יהיה חרות אלא את אשר יצייר כנגדו ולצד עוצם תוקף אורו יתברך לא היה אור של הלוחות יכול עמוד בכל המקום אשר יכוין כנגדו אצבע אלהים והיה נאכל או מתצמצם לצדדין והיה נשאר כל אשר יצטייר כנגדו חלול ולזה נכתבו משני עבריהם"...‏

The words: "written with the finger of G'd" mean that G'd drew the shape of the letter with His "finger," i.e. using one of the kinds of light at His disposal. It (the light) assumed the appearance of a finger opposite the Tablets corresponding to the dimensions of the requisite letter G'd wanted to inscribe. G'd did this in order to ensure that no more and no less than the letter should be engraved on the Tablets themselves. Seeing that the light G'd used to do this with was more powerful than the light the Tablets were made of, the light of the "finger" penetrated the requisite area of the Tablets. We may perceive of that area on the Tablets as having either been devoured or pushed aside. What remained were holes forming the letters G'd had engraved. Thanks to the superior power of the light of the "finger" the inscription became visible from either side of the Tablets. This is what is meant when the Torah wrote in 32,16, that the Tablets were written from both sides, i.e. that the inscription was deeply engraved. The Torah uses the expression חרות על הלוחות "engraved on the Tablets," instead of saying חדות בלוחות, engraved in the Tablets. This is the allusion to G'd having placed His finger "on" i.e. opposite the material of the Tablets as we have explained.