Hang Your Glass designed the locking stand-off so that only one should be used on a piece of glass. If your glass is larger than 10" x 10" then you should consider using the Round or Super Duty stand-offs.
The Hang Your Glass adhesive is "stronger than the glass". It's a critical component to the effectiveness when hanging your art glass. It sets in 5-10 minutes, good for indoor/outdoor use and lasts over 300 years once it cured.