If the left sysdate is aways evaluated before the right sysdate, a discrepency would not matter.

If the reverse happens, you are SOL.

And, since the right is in a parens as part of a function, my guess is that it could be evaluated 1st.

You are right, this is scary usage.

Change the right one to "sysdate+1" and it will NEVER be too early. Document it well.