It would be nice to have buttons with names of standard series E12,E24, etc. next to value slider. Then slider should only use standard values. It is better to use only values that you can then use in real circuits. We rarely use other capacitor values than those from E3 or E6 series. Resistors usually only from E24 etc. The same limitations may be added to zener voltages. There are standard values like 4.7V, 5.1V, 5.6V etc. Why to use 4.8V zener in simulation when you can’t buy one.