Is the N amount per month? Like GreenDoc and others said you may cut down on the N. I deal with these same 2 grasses as well as zoysia & St Aug. Pretty hard to let healthy bermuda go 2 weeks between mowings without cutting excessive amount off & scalping. On the centipede I usually go 2 weeks between mowing unless we are receiving alot of rain which we haven't for several years. Do these people have irrigation? Probably the biggest obstacle I face is getting people to water correctly. When practical I simply take it over. I have tried Mesa fert and am having good results so far.