Indeed, a user can mark as many forum posts in his thread as he wants. Additionally, all forum threads are reviewed by a Telerik representative within 72 hours and if in this period there is a correct answer which, however, is not marked as an answer, the Telerik representative may mark it, so other users can scan through the thread and find the needed post(s) right away.
I hope you find this information useful. Should you need any other assistance, do not hesitate to contact me.
All the best,
the Telerik team