The length of sorties will depend on which aids you require, and your distance from them. I.E if the nearest VOR is 120nm away then the flight will be a long one.
I suggest you look at the type of aircraft you will be flying after your rating, which instruments it is equipped with, and the approaches available at some of your intended destinations. Remember, private IFR you can nominate which aids you want to be endorsed on.
RNAV/GNSS approaches are everywhere (almost) but unless you are flying into some serious aerodromes, or military, then ILS is probably a waste of your money.
I did the MECIR part time, and as long as funds are available 2 flights in a weekend is certainly do-able.