Hello, Greetings! of the day. As mentioned in project description, your requirement is to implement custom data manipulation functionality for plugin "WP All Import", to import values in "tag" field, according to day of week, as follows:
1) In first import - Monday, the value should be 240-0=240.
2) In second import - Tuesday, the value should be 240-48=192.
3) In third import - Wednesday, the value should 240-72=168.
4) In fourth import - Thursday, the value should be 240-96=144.
5) In fifth import - Friday, the value should be 240-120=120.
6) In sixth import - Saturday, the value should be 240-144=96.
7) In seventh import - Sunday, the value should be 240-168=72.
8) In eighth import, the function of first import should be applied, that is, the value should be 240-0=240. So, every week, on Monday, the formula is reset.
To implement this functionality, the custom code will need to be added, using hooks and filters of plugin "WP All Import", to manipulate import data, before it is imported.
I have much experience in working on projects, using PHP, Wordpress, "WP All Import" plugin. Your work will be done, according to requirements.
Thanks.