A standard technique for monitoring software testing activities is to instrument the module under test with counters or probes before testing begins; then, during testing, data generated by these probes can be used to identify portions of as yet unexercised code. In this paper the effect of the disciplined use of language features for explicitly delimiting control flow constructs is investigated with respect to the corresponding ease of software instrumentation. In particular, assuming all control constructs are explicitly delimited, for example, by END IF or equivalent statements, an easily programmed method is given for inserting a minimum number of probes for monitoring statement and branch execution counts without disrupting source code structure or paragraphing. The use of these probes, called statement probes, is contrasted with the use of standard (branch) probes for execution monitoring. It is observed that the results apply to well-delimited modules written in a wide variety of programming languages, in particular, Ada.