I have an SMB and a finger spool on every ocean dive, and I deploy it on almost all of the dives as well. Here in Thailand, most of our dives are drifts, but even when I'm diving in a bay and am expected to return to the anchor line, I deploy the sausage. This serves both to mark our position for passing boat traffic as well as to alert our boat that we will be ready for a pickup shortly. For drift dives, our boats know more or less where to expect us to come up, and when the dive time is about up, they move in to the area for pickups, scanning the water for the markers. If a diver/group isn't on board as expected, then the crew will continue to scan the water until we/our sausage is located, and then go pick us up. We deploy a sausage when we begin the safety stop, but we do not tow a marker during the dive. We very rarely have a case of a lost divers/groups here in Thailand--certainly not as often as seems to happen in other parts of the world--so I guess our system is working well.