saudipc-9 for sure there is no one size fits all when it comes to flying in the vicinity of thunderstorms and most flying today is done in areas of the world where there is very good weather forecasting and real time weather available.
However, there are areas around the world where low level weather forecasting and real time weather is sketchy to say the least.
Bearing in mind penetration of active fronts in the lower levels ( Below FL180 ) is a high risk part of flying for sure, so if faced with no choice but to penetrate an active frontal system the lower you can safely fly through it the better your chance of safe passage, and also once committed to flying through it try and penetrate the front at as perpendicular a track as possible to give the least time in the front.
Back before the days of GPS I was ferrying a PBY over the ocean and ran into a situation where I had to get through such a front and at the time I was flying in T effect for lower fuel burn to extend my range and found that staying at one hundred feet allowed me to pick my way through the heavier rain due to being below the cloud and also the vertical air currents get flattened out at the surface and the up and down movement of the airplane is cushioned by the descending air bursts being flattened out at the surface.
It was not pretty but considering how violent those same up and down air currents would have been a few thousand feet up it turned out to have been a smoother ride.
ONCE AGAIN!!!!
This discussion is not meant to be used as a suggestion that this type of flying is something to be treated lightly, it is meant to be a discussion on how you may mitigate risk when there is no choice but to find a way through a frontal system.
Fortunately the days of flying old low performance airplanes in remote parts of the world with ancient navigation equipment is getting to be very rare, but there was a time when that was part of being a working pilot.