When I started WaniKani I also wanted to be able to write all of the Kanji I learned (both for retention, differentiation of similar kanji and simply being able to write the solutions to my exercises…)
Honestly, learning to write Kanji takes me only about 15min a day by using this WaniKani Anki writing deck.
I imagine most people can probably include those 15min in their study routine without trouble, and I highly recommend doing so as the value of being able to write is well worth the 15min of extra study!