Second Above poster.
The "strength" of a cadence actually refers to dynamics, stress, and things of that nature. Sometimes the strongest cadence is a short one, like in Beethoven's fifth (arguably long)
If I play V7 - I with the soprano resolving up (leading tone) to the tonic with the bass landing on the tonic I can increase or decrease the strength of it by playing it again, using a "cadential extension" by playing the bass note again or playing a scale and repeating the cadence, holding the I chord longer than the V7, trilling the top note, using suspensions, etc...
The first thing you should figure out in song design is what kind of cadence you want to end in, which in my writing changes like my underwear. If you are playing a sad song, you won't want to end on a PAC unless you are trying to be positive. You might choose a half cadence like many pop songs, I-V or anything to V, which is considerably strong anyway due to its nature of makeing you feel like the song pushed you off a cliff without a parachute. Then after deciding what type of cadence you want, then you choose the strength. The chord progression and the dynamics and speed of the song BEFORE the cadence play just as much of a part in strength as the actual cadence itself.
Final point for me, if the song is fast and loud at fff, then a piano to forte V-I with a long of stress on the I won't be very powerful, but in a slow mf song, the same cadence would be strong.