not at all. Running the engine for short periods, in a car that is out of use, will cause acidic condensation in the engine, oil, and exhaust, leading to corrosion.
If you have, or can get, a battery charger, about once a month will do. If the battery is old and will not hold its charge, twice a month. Take special care to keep it charged in winter, as a flat battery is more able to freeze. A low power charger will do as you are not in any hurry. You will see the ammeter needle (or the indicator lights) on the charger drops down as the battery charges up, then you can disconnect it. Ordinary chargers should not be left connected for more than about 12 hours, overnight is usually enough. There are some quite expensive "smart" chargers that can be left connected permanently for laid-up cars, but you don't need one. Even a low-price 4-Amp charger will do a small or medium car in about 10 hours. very likely a friend or neighbour will lend you one, they are useful to have but very seldom needed. A battery will be damaged if it is left discharged over time.
At this time of year supermarkets often sell cheap chargers in the hardware aisle with windscreen wipers and motor oil.
BTW if the battery is new and went flat quickly, next time you charge it, go out after dark and look for something left on, usually the interior lamp or the light in the boot. An alarm sensor will gradually discharge the battery, but should take a couple of weeks. If you turn on the headlamps, and they have gone dim by the time you get out and look, the battery needs charging again. Also charge it up the day before your friend is ready to use the car again, for an easy start. It is possible to test a battery's state of charge using a voltmeter, but I don't think it is worthwhile in your case.