The question you need to ask, what is the critical parameter you need out of this capacitor?
Do you use it to store as much energy as possible (exact amount of capacitance matters, more is better), or do you use it to respond to quick changes of current while minimizing voltage change (exact amount of inductance matters, less is better)?
If it is a 10uF part next to a gate driver driving 1nF worth of equivalent gate capacitance, then obviously it doesn't much matter if it's actually 10uF or 5uF, only ridiculously tiny part of that charge is used to deliver 1nF into the MOSFET. This is the general case with IC bypass caps - they are used for lowest possible high-frequency supply impedance, exact amount of capacitance is irrelevant.
For the same reason as placement is important, so is small package size.
Sometimes you want both minimized inductance and nontrivial amount of capacitance (say more than 1uF, so you can't just slap in any 0402/0603 and call it a day). In such cases, paralleling multiple capacitors (of exact same type/value) offer layout benefits as you can sprinkle them to conform to your other components. For similar reason, try to use at least two vias per pad when going to another layer; giving more parallel routes to the changing currents reduces inductance.