DNS and other medics would suggest that there is no such thing as too much insulin to take at one time. A lot will depend on what you eat,and what your ratios are
My ratios are quite high (considering BMI and low doses until changeover to basal bolus from premixed) and I dont each any more than 100g per day carbs at the ABSOLUTE top end of carbs, more like 80g average. I do however think because of this my body is very adept at converting protein to glucose (or else I would have keeled over by now presumably) this does impact on it
So, if I want 30g carbs I need about 5.5 u Novorapid. Morning ratios are ridiculously high (often 5u for 10g bit toast- hardly worth it, though prob warding off lack of basal combined with DP).
So, it will depend on what your ratios are, what you eat and what you are happy taking ultimately. In theory no amount is too much, but its really what you are happy with and the less you take, the less likely you are to gain weight, and the margin for error is lower