ICC have taken T20I seriously, as we had regular 3-match series played across the globe in bilateral contest this year.
I believe it is important to take this format very seriously, and have mandatory of minimum of 3-mach series between teams whenever teams play bilateral multi-format series.
This year despite higher frequency of 3-match series, we still had 6 one-off /two-off series contest between teams.
One can understand packed FTP schedule, yet T20I requires consistent matches to be played throughout the year. The flow will allow teams to field a consistent XI, allowing them to have different personal for each format, and by doing so they can have a larger pool of Int. cricketers.
This (2018) year is a great example of No. of matches played. At end of IND -WI series 74 matches were played with 51.35% success for team batting first. It has been a batting paradise – with Avg Score for 1st batting team has reached the highest in history(2005 onwards) of T20I!.
On 17th Nov, 2018 South Africa will be facing Australia for the first time since T20IWC2016 in a one-off T20I. Last they met was in Sept 2016 -a 3 match series in South Africa which Australia won 2-1.