On Succos, how many times a day does one say "lashev b'sukka"?
- Once a day at the onset of daylight?
- Once at day and once at night"?
- Every time one enters the succa to eat?
The rules are just like the rules for Tefillin and Tzitzit (Sukkah 46a). The blessing lasts until you leave the Sukkah (or remove your Tefillin, etc.) without intending to immediately return. If you stay in your Sukkah all seven days then you never make a second blessing. If you leave for a while and return you make a new blessing. The popular practice when entering a Sukkah anew is to delay the blessing on dwelling in the Sukkah until it can be adjacent to the most established form of dwelling one does in the Sukkah. (See Mishna Berura and other commentaries to OC 639:8 for details.)