you need an excuse
My thinking process when learning and applying IFR height requirements has always been "you need an excuse to be where you are" (in altitude).
So anywhere along your flight you should be able to ask yourself "am I allowed to be here" and the answer hopefully will be something like:
- yes I'm above the route LSALT, or
- yes I'm established within 25nm and above the MSA,or
- yes I'm within the circling area, or
- yes I'm above the relevant DME step (also handy to apply in reverse on departure)
- etc etc
If you can't think of an excuse straight away then you had better be in day VMC which is your last option. There are no loopholes in IFR requirements, smarter people than us would have found them by now and punched themselves into a hill somewhere.