There's plenty of reason. When they had toxic debt that creates a complex derivative liability and every note and conversion triggers different valuations. It's time consuming to do all the recalculations
Yes, you're right. There's no telling. Completing a 10K is a time consuming, tedious process. If you're staffed lean and trying to save money where you can you try to do the work yourself instead of paying your accounting firm. Travel, sales, R&D can all get in the way. The K is one of the biggest accounting tasks of the year for any company.
Maybe they made a strategic decision to bundle the Q4:K and Q1:Q together and release them together for impact.