I find glassing is particularly useful if there is very little structurally holding two wings together. I am refering to to flat rib pieces and a small plywood joiner. There is not a lot of interconnection between the two halves and if a small piece of the structure at this weak point in the assembly fails then there is not a lot of backup holding them together. if the two halves are built together or have long plywood joiners that connect tightly to the spars then glassing is not as necessary in my opinion. Wing halves should always be expoxied together with 30 minute epoxy unlike some instructions that say slide wings together and secure with a strap and screws. I have seen a few of those screws come out and wings separate. Another good use for glassing a wing is that if the wing is mounted by rubber bands the glassing keeps the bands from digging into the wood. On bolt on wings I always glass a small area around where the bolt holes or drilled through to give the wind more ability to resist the bolt being torn through. I know the wing bolt holes don't normally see a lot of stress but the stress sure mounts up when the wing decides to shear the bolts by saying hello to the ground. This has allowed me to be flying the same day on a slightly bad landing or cornstalk engine out landings.