Apple Watch airplane mode disadvantages?

Since a few days I have an Apple Watch and I really like it. I just wanted to know if I could use my watch in airplane mode all day, and at the end of the day I connect it to my iPhone to let all my health data sync. Is this possible? How long does my watch collect data when it isn't connected to my iPhone? Today I woke up very early in the morning and I put on my watch (in airplane mode). A few hours later, I disabled airplane mode and all my health data from the last few hours (e.g. heart rate) was synced immediately to my iPhone. Does that even work when my watch is in airplane mode the whole day?