Writes values to Tags at the given paths. This function will "block" until the write operation is complete or times out. Meaning, execution of the calling script will pause until this function finishes. This useful in cases where the tag write must complete before further lines in the same script should execute.
The script in your first post is fine, no need to wait. You could maybe check the result of the first call is good before doing the second, if that matters.
This. Check return values from the OPC write operations. (In case it isn't obvious all over the place, I hate using time in a sequence if I don't have to.)