Too much is when you have reached the limits of the available cam cores, cores are only hardened to a depth of around .060, which limits the lobe lift, duration and LSA on that particular core. A billet core does not have the same limitations, so by playing with a little math you can go just about anywhere. Using Jeff's example above, a 266-284-116 has an overlap of 43 and when installed at 111 yields an IO 22, IC 64, EC 21 EO 83. By using the same lobes and increasing the LSA to 118, now you have 39 overlap, IO22 IC64 EC17 EO87. If you wished to keep the overlap constant but widen the LSA, the 266-284-116-43 could become a 270-288-118-43, or even a 274-292-120-43. The hard answer is to use whatever LSA suites the desired opening and closing numbers. Your cam grinder will advise you if your numbers will not fit his available core choices.