Yes the issue cheque first tactic is useful to close the deal. Only the serious and sincere buyer will agree to do that. But agents wont "ALWAYS" will says and use this tactic. Its depend situation and cases. FYI i just close a RM3M sale by using this tactic and its buyer offer issue cheque first. No hurry to buy, not necessary to buy this unit but to show sincere not play play look see type. And, for nego the price.
About the super busy agent. Not sure its the agent is really that busy or its might be from the owner side. Because for this type of fix time normally is set by the owner. I have met some owners is like that. Only certain time and date can view the unit. This is mostly either to meet the tenant time or the owner busy time. Not easy for me to arrange for viewing also.