Biconcave shape of RBC is useful for all, EXCEPT:

Biconcave shape allows easy folding of RBC on itself when it passes through capillaries. It allows considerable alteration in cell volume. Thus can withstand considerable changes of osmotic pressure and resisit hemolysis. Also Know: In humans, they survive in the circulation for an average of 120 days. The average normal red blood cell count is 5.4 million/L in men and 4.8 million/L in women. The number of red cells is also conveniently expressed as the hematocrit, or the percentage of the blood, by volume, that is occupied by erythrocytes. Each human red blood cell is about 7.5 m in diameter and 2 m thick, and each contains approximately 29 pg of hemoglobin. There are thus about 3 x 10 13 red blood cells and about 900 g of hemoglobin in the circulating blood of an adult man. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 31. Blood as a Circulatory Fluid & the Dynamics of Blood & Lymph Flow. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e