Does the time spent at competitions count in the hours spent per week.

I am in Boxing and in addition to our practice hours of 2.5 hours per day (12.5 per week)… we have competitions every Saturday. How should I include that time?

Competition is from 8am to 5pm

Match time is like 4-5 minutes and I only have like 4-5 matches usually.
However, there is warmup, prep, constant practice to keep myself ready so the time in between next match should count too right?

If these are team events, and you are expected to remain at the meet and cheer on the rest of the team, then you should count the entire length of the match. Participation is not just your direct preparation and participation. You are a member of a team, and supporting your teammates is participation.

Here is a formula you can use: Total amount of time spent on extracurricular/number of weeks spent on extracurricular=time spent per week.