Nearly a 100 years ago a Professor of psychology decided to test and robustly answer this question.
She took 4th and 6th grade school students and decided to test the effectiveness of praise vs criticism via a class of mathematics where the results could be measured.
On Day 1 the class was divided into 4 groups. All 4 Groups took the first maths test and then 1 group was sent to another room to serve as the control group.
The remaining 3 groups received over the next 4 days the following treatment from the teacher.
Students in Group 1 were appreciated in front of each other for their performance.
Students in Group 2 were criticized for their performance in front of others.
Students in Group 3 were left alone. Ignored.
The results.
By day 5 the evidence was incredibly clear.
Group 1 which got the praise showed an amazing 71% improvement in scores
Group 2 which got criticized showed just 19% improvement in scores
Group 3 which was ignored hardly showed any improvement at 5%
Many more studies in the work environment show the same thing. Appreciation when done genuinely and with a specific area of feedback to the individual leads to powerful results and strong engagement.
There is no such thing as too much appreciation.
Identifying what is good about each person and finding specific areas they did well in is a powerful motivator for us all.