excessive in amount or degree
inordinate - excessive
Something that exceeds normal limits regarding amount or extent in a negative way can be referred to as ‘inordinate’. The word is most commonly used in relation to an excessive amount of time spent doing something, but can be applied to a number of other contexts too.
Just leave that task and move on to something else. You've already spent an inordinate amount of time on it!
We’ve had an inordinate amount of meetings this week. There’s too much talking and not enough action going on.
When applying for a bank loan, I was expected to fill out an inordinate amount of documentation. The process needs to be streamlined.