I think personally it is way easier for me to do it that way. Let's say we have 6.687-4.798, then think how long it takes to solve this problem versus just solving 6.700-4.800. Does that make sense?
Estimation is a important skill to know when adding and subtracting decimals because if you estimate you have an idea on what your answer should be close to.
For example 4.68-2.38 could be 5-2 which is 3. 4.68-2.38 equals 2.3. 2.3 is close to 3.
