If you see gaps in where your pointing should be then it is time to consider having that particular section repointed. Repointing is essential to you house as it helps structurally but the mortar also protects against water ingress, preventing heat loss through the walls. When rain does come the water can freeze into the bricks and surrounding mortar thus expanding which eventually causes damage. If this is neglected it can lead to a damp and cold house.
Repointing is essential to your home as if an area that requires repointing is left for a long period of time it can spread & cause severe brickwork damage. If the crack spreads it can also be a lot more costly as a pose to if you have the repointing done before hand. A lot of customers do choose to also have a masonry sealer applied after the repointing service.
The purpose of the masonry sealer is to protect the current brickwork & combat against any further damage which may occur in the future.
Benefits of repointing
Repairs the structural integrity of your home.
Maintains and possibly can increase the value of your home.
Ensures weather guarding.
Reduces heat loss.