Upvote:4
If it is a multiple entry visa, you can stay for a total of 16 days (the first and the last count as full days) during the period of validity, with a gap in between. So you can adjust the dates of your travel as long as you have days left.
This does not apply for a single-entry visa.
Upvote:7
My question is: would it be possible to fly out off Czech Repubic for a day or two and then back to Czech Republic to stay longer than 16 days stated in the visa?
No.
The "Duration of Stay" dictates how long you can stay in the Schengen Area between the "From" and "Until" validity dates on the visa or in compliance the 90/180 day rule (depending on which applies in individual cases) - it does not reset on a border hop, it is not per trip, it is total.