UTR in uses your last 30 matches to determine your rating one year from now. So in general you want to keep your last 30 matches as close as it is to today's current date so it will match your current playing level. Many players don't even play 30 matches in a year so this means that their UTR uses matches from a year ago. To combat this it is better to play more matches consecutive in a short period of time to reflect your current playing.