Do you advice me to use fixed periods instead of each year in fixed effect model ? Why?

Thanks for invitation,

In statistics, a fixed effects model is a statistical model in which the model parameters are fixed or non-random quantities. This is in contrast to random effect models and mixed models in which all or some of the model parameters are considered as random variables.

In many applications including econometrics a fixed effects model refers to a  regression model in which the group means are fixed (non-random) as opposed to a random effects model in which the group means are a random sample from a population. 

consequently, I do believe that matter is subject to the application which are used and its parameters.