A SuperDrill can last only for a few seconds, and I know you would love to have this beast for a few more seconds. Well, you can boost Magic SuperDrill duration by increasing its stats. To do this, you will need to equip those items that add magic points to the total Magic SuperDrill stats. You will also have to craft different types of items and imbue them to add more magic points.
The Magic Super Drill duration increases by 1 second for every 10 points of magic added to “Magic SuperDrill” stats, which can be accessed by tapping the helmet icon on the home screen (check the screenshot above ). It will take you to “Your Gear” section. If stats show “10”, then the superdrill duration will be increased by 1 second. At “20”, it will increase by another second and so on.
You can check how many extra seconds you received by increasing magic by tapping a level on the level map. Bonus seconds will be shown under the quest description.
Source: Tiny Miners: Tips, Hints and Strategies to Become the Best Digger
As mentioned in the comments below, the answer was not satisfactory.
However, the following does:
The last line of the shown pop-up indicates that each dungeon has "magic setting", which will affect the duration of your Super Drill.
Those "magic settings" can be found when selecting a mine and will show at the top. It says "Superdrill duration" with a total time and an indication of the time that has been added by your Magic Skill.
So you may be correct about the duration feeling lower and lower in each new mine due to higher mines having higher "magic settings".