https://mwi.usma.edu/russian-ukrainian-war-understanding-dust-clouds-battlefield/
Nothing ground breaking,(or political, I believe).
Still, useful for pointing out a possible Russian preference for sustained political pressure maintained by sustained military pressure.
There could also be logistical/force sustainment considerations, but nothing Putin couldn't brush past if he so wished.
When I started properly reading up in this nasty fight I'd initially wondered why Russia didn't go for a desert storm style strike. However it was described to me here and elsewhere, that choking an unfriendly regime, rather than can crushing it and dealing with a massed resistance, is better in many ways.
Follow Up commentary:
http://www.dupuyinstitute.org/blog/2017/01/21/an-additional-comment-on-the-link-between-operations-strategy-and-policy-in-russian-hybrid-warfare/