Where two line items each have a different timescale, and one refers to the other in a formula, then days will aggregate into months, months aggregate into quarters, and quarters aggregate into years.
You can choose to skip levels: days could aggregate directly into years if required.
If line item X has a timescale of Months and line item Y has a timescale of Years, then
Y=X
will return the year total. However;X=Y
will return nothing because Y contains no corresponding value for each month.
Formulas using the WEEKVALUE, MONTHVALUE, QUARTERVALUE, YEARVALUE or SELECT functions can be set up to return the result required.
For example, if X is in Months and Y is in Years:
Y  Years = Month Data

Result takes the relevant time total from Month Data, when Month Data has a more detailed timescale than Y  Years. 
X  from X in Time Aggregation  Year

Shows a blank, unless Summary Method is set to Formula, in which case it will show the value Y in the year totals only (highlighted). 
X = YEARVALUE(Y)

Will show the value of Y in each month. 
X = YEARVALUE(Y)/12

Will allocate the value of Y evenly over months. 
X = YEARVALUE(Y) * Seasonality%

Will allocate Y according to a seasonality percentage (not shown). 
X = Y[SELECT:Time.FY11]


Remember! When you use any of the time functions, such as WEEKVALUE or MONTHVALUE, the value returned depends on the Summary method set for the source line item.