Okay point taken, he's made 8 meaningful contributions in 144 innings, my mistake...
How many of his centuries has he scored without somebody else bringing theirs up 1st?
Does it make a difference if someone had scored 99 before him or 100? does that 1 run change a Bell innings from being easy to acceptable? What about if it was 93 or 84?
Has I have said before Bell has spent a large chunk of his career coming in behind Strauss, Cook and KP, three of Englands top six hundred makers of all time. There is a fair chance then that someone will have scored a hundred before him with those 3 in the team.
In answer to your question I have counted 4 instances of Bell reaching three figures before somone else does, incidently that is the same number as Gilchrist. Does that mean Gilchrist is only capeable when he has got runs on the board?
I presume you also feel that Compton hasn't achieved anything as both of his hundreds came after someone else had scored one and considering he opens the batting surely he should be getting there first?
If you are going to judge Bell by this irrelevant statistic you have to apply it to everyone else.