50 Hourly's
If you loook at the MR all checks and maintenance are written in the same section, headed up by "Maintenance Required" if you have a 50 hourly written in this section, it as to be done at that time. Some LAME's enter it as 50 Hourly recommended to try and say that it doesn't really need to be done then, and maybe +- 5 or so hours is OK. But the bottom line is that if it is written in the Maintenance Required section it has to be done. If you are just doing 50 Hourly oil changes and aren't required to do them simply don't have it written in this section, and complete the 50 hourly as close to 50 hours as you can thus giving yourself +- 5 hours if required.
Cheer's