Just to be clear, I am an altar server at Mass and a sacristan. I will pass both the altar and tabernacle closely during and outside of Mass.
The answer depends on how your sanctuary is configured architecturally and the placement of the tabernacle. What to do isn’t always clear in some Churches. In my Church, for example, the tabernacle is in the sanctuary but off center, to one side. It is very prominent, but not directly behind the altar.
Outside of Mass (since this is your question) I bow when I pass the center of the altar. Whether it is behind the altar as when I am lighting the candles, or in front of the altar when in the main Church.
I genuflect when I pass the tabernacle closely. The door to the sacristy is close to the tabernacle and so I generally genuflect as I enter and exit the door.
There are exceptions however. If the Church is full of people and I walk down the main aisle, conscious that people are watching, I will genuflect to the tabernacle when I reach the end of the aisle at the base of the steps to the sanctuary.
Also, whenever carrying something I will generally bow. When carrying something heavy or bulky, like a kneeler or the stand for incense, I will just keep walking.
I also give consideration to the people I am with. I’m not about to genuflect if I am with a priest who only bows to the altar. If walking with a priest I will walk behind him, hesitate for just a moment, and do whatever he does. I’m not about to embarrass the priest. I once walked to the sanctuary with a bishop - walked behind him and did exactly what he did.
Hope this helps in some way. My Pastor always says, “Make it look reverent and consistent. Other than that just do the best you can.”
-Tim-
