Your calculations are a bit wrong . For excercise , the calculation of profit will be (140-105-9.5)*3850 . Anyway , it doesnt matter much if you excercise or square off on the lastday of expiry ( unless you sq.off it at high price and price drops later in noon ) . It definately matters , in all other days as options carry some premium . One more important thing is , when the call is too much in the money , the volumes will dry up and sq.off those will become difficult .
Example : i bought neyveli 115 call at 7Rs . On the day of expiry neyveli went to 135 but there were no buyers for the call . I excercised the option and got the closing price at 129.95 .. 5rs is huge differance and thats the problem with illiquid options . ( I did short neyveli fut at high so that my overall profit will be same , but we may not margin to do that all the time . better avoid illiquid options or if you did enter try to book as soon as possible
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Naresh