I'm on a retirement visa so I usually have all the time in the world. It's just common sense to arrive early and dress respectfully. However incompetent or corrupt they may be, it's still their country and their rules.
never had many problems. Turning up in high season when they are busy and I just happened to pick the day when there was some gobby tosser, plus a scruffy drunken twat giving every one earache and a hard time, I was delayed slightly on a 90 day stamp. Ho hum.
I did get a hard time on annual renewal of permission to stay at the Surat Office last year. This year I just went to a different office. No problem renewal sorted.
Most problems can be put down to stroppy punters or staff changes. New boss or quality long term staff getting moved/promoted.