Please set entries initially not to zero but to "no value" to avoid totally wrong entries!
When using Crono regularly, I find the only efficient way of usage is to use the "copy current day" function intensely. This works like a charm for all standard entries of a day like how much I have slept or what my weight is or how much butter I have eaten. But there is one big issue: Over time, this creates a lot of wrong entries: I copy the day but certainly oversee changing this or that entry. So it will stay on the value as copied. I have regularly errors like this. The solution would be: copy the current day to a future day, pad everything with "no value". Then use this as a template: copy it back to all days.
Anyone a more simple solution?