Please dont leave tests, its a mistake which will cost you at the end. I understand your situation. Give more time to your NEET Preparation, and mostly Tests are in weekend so you may get a Day or Two (Friday-Saturday), around 30 hours of the total 48 hours on both days are enough for Mock Test Preparation, provided you are regular with NEET Preparation and Revision. Keep Arihant/Allen Handbooks and Formula Books with you as well as Chapterwise Previous Year Books for Short Notice Test Preparation.

As far as your School is concerned, keep your Attendance full, doesnt matter if you have a moderate performance across School Tests provided youre understanding the concepts, target securing High Percentage in Pre and Board Exam. You may utilise any free time during School wih MCQs or Previous Years, or analysing and noting down errors from your Previous Test.