It will make for quicker transitions. If you rubber band them to the bike while setting up your transition area prior to the race then out of T1 you can do a running mount to get on the bike. For entering T2 a little bit before the dismount line you get your feet out of the shoes and put your feet on top and then when you jump off at the dismount line the shoes just stay with the bike as you head to T2.
If you are new to running mounts and dismounts then I would practice them in a grassy field in case you miss once or twice and fall. Pavement is a lot less forgiving than grass.
It also matters what kind of shoes you have. Some are easier to slide into on the fly. I have the Specialized Sworks Trivents which has the heel that drops down and makes it stupid easy. When you turn the wheel to tighten the shoes the heel pops up and tightens as well.
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If you are new to running mounts and dismounts then I would practice them in a grassy field in case you miss once or twice and fall. Pavement is a lot less forgiving than grass.
For the visual learner this is the idea: