opscode/epgsql — comment on commit 7b0e0118e70d57407ce030f7515182cc44c603d5
File:  line 0
By mabrek:

not every Execute requires Sync, you can send several Binds/Execute and then one Sync.
from the linked documentation
"The purpose of Sync is to provide a resynchronization point for error recovery. When an error is detected while processing any extended-query message, the backend issues ErrorResponse, then reads and discards messages until a Sync is reached, then issues ReadyForQuery and returns to normal message processing."