I have crossed by land on F1 and more recently on B2 without surrendering my I-94. On F1 (and H1B), the expiration of the I-94 is duration of status (D/S), and if you intend to return within 30 days, you do not need to surrender it. As to the B2, I read that you could ask the CBSA officer in Canada to take it, if not, you are responsible to mail it back to the address noted in the back of the card to complete your exit record. I subsequently flew back to the US on the same B2 and I-94 for a wedding and at the YYZ pre-clear POE, the CBP officer didn't ask anything, but he did not issue a new I-94 stamp either. I surrendered it to the airline when I returned to Canada after the wedding.
Long story short, if you are going to Canada and returning the same day, keep the I-94. You won't run into trouble and you won't have to go into secondary either when entering the US. I did that many times on F1 while attending a cross border program (attending both US and Canadian universities at the same time).