Based on the screen functionality & complexity of the 
logic, we can identify the defects. Whatever the screen, I 
test with respect to Unit Test Case Document. I will verify 
all the conditions and give the bug report.

In addition to BTech[wipro] comments:
The Bugs i find in a Day could be 
an User Interface deffect Bug,
boundary related,
Database Related,
Error Handling deffect,
calculation deffect
Load conditions,hardware failures,
Compatibility related.

It depends upon the no.of requirements.We may not find even 
a single bug in a day.

If found, these are the  various types

defects which deviate from the expected functinality.
defects related to script errors,Date format errors,invalid 
date and data
cosmetic defects (irregular font size of text,irrelevant 
data(like reverse question marks in the middle of the text),
etc....,Missing functions.

it also depend on the test lead - who gives the role to 
play - to which part we have to concentrate - each and 
every person can find many kind of bugs as mentioned by 
btech, lax and murthy - the role and the case assign to 
them in that test case the will find the bug and it also 
depend on the programmer if he is good enough we may find 
less if he is bad we will good in finding all the bugs