As bodom says, it's possible, and extremely useful, to do noting continuously on a retreat. It can be usefully done through certain everyday tasks, those that are mostly physical. However, it's going to get in the way of tasks requiring conceptual work (reading, writing, studying, etc).
I made some comments about this here: viewtopic.php?f=41&t=11240#p169548
One interesting observation came out when I asked [my teacher] about how to maintain mindfulness in "normal life". His reply I reword/summarise as:
The point is not so much to be trying to take techniques from those suitable for retreat training in continuity of mindfulness, etc, but to use the wisdom gained from retreat training.
i.e. on retreat one can carefully observe to determine what is skilful (or not). That's ideally what one should be doing at all times. Techniques such as doing everything slowly and deliberately are not so practical in normal circumstances, but its the quality of observation, rather than some particular technique, that needs to be carried over.