Shingle sealing arrangements

A shingle system comprising:

• at least one overlying shingle comprising at least one coated shingle sheet defining a headlap portion and a tab portion each having opposed upper and lower surfaces;
• at least one underlying shingle comprising at least one coated shingle sheet defining a headlap portion and a tab portion each having opposed upper and lower surfaces;
• the at least one overlying shingle having a plurality of round dots of sealant applied to the lower surface of the tab portion;
• wherein the plurality of round dots of sealant comprise both:
• a) round dots of a first sealant formulated to seal at a temperature of less than 70° F., and
• b) round dots of a second sealant comprising a thermally activated adhesive having a minimum activation temperature of at least 70° F.;
• the at least one underlying shingle having a channel on the upper surface of the headlap portion that is free of sealant;
• wherein the plurality of round dots of sealant of the at least one overlying shingle contacts and adheres to the channel of the at least one underlying shingle when the shingle system is installed.