Despite it being as difficult as your first exposure to algebra. Holding a handstand on the floor is just the beginning of possibility. Having exposure to other platforms will be beneficial in learning nuances of the inverted body, familiarity with different apparatus, and strength development from the change in musculature. Practice all variations frequently. 

1) Max Time in Handstand on Parallette in 3:00

2) Max Time in Handstand on Blocks in 3:00 

3) Max Time In Handstand in 3:00