Flat electrolytic capacitors and methods of making and using same in implantable medical devices (IMDs) are disclosed, the capacitors having a plurality of capacitor layers of an electrode stack formed of tailored numbers of anode and cathode layers to fill the available stack height space in the capacitor case. The capacitor is formed with a capacitor or electrode stack assembly having a stack assembly thickness or height HN that is tailored to fit a case wall height Hcw of the capacitor case with minimal wasted space and allowance for any stack height tolerance to. The electrode stack assembly comprises a plurality of N stacked capacitor layers each having a specified capacitor layer thickness or height. At least N1 capacitor layers have a first capacitor layer thickness T1 and N2 capacitor layers have a second capacitor layer thickness T2 where N=(N1+N2), and HN=N1*T1+T1*N2. The N capacitor layers are preferably formed of a cathode layer, and anode sub-assembly and at least one separator layer comprising one or more separator sheet on either side of the cathode layer and the anode-layer sub-assembly. The anode sub-assemblies of the N1 capacitor layers comprising x anode layers each having anode layer thickness tx stacked together, each anode layer having an anode layer thickness Tx. The anode sub-assemblies of the N2 capacitor layers comprising y anode layers each having anode layer thickness ty stacked together, each anode layer having an anode layer thickness Ty.