Will I face issues traveling to Thailand multiple times a year on a tourist visa?

You could also get the DTV visa. That one will let you come and go as you want over the next 5 years with a maximum 6 month stay each entry.

as people stated, it is doubtful you will have much issue with that planned travel because you're not taking the full 60 days you're stamped in for, and you always have proof of onward travel (that you're leaving)

Your travel plans are not out of the ordinary, and I'd say it will work until it doesn't 😮 which no one can predict,

BUT in your favor, you are not milking 60 days plus taking a 30 day extension then bouncing out/back to do it again. you have time out of the country between your trips and they are shorter than you get stamped in for, you should be okay

I have a friend who works in NZ and has been coming here for about 7 years visiting about 3-4 times a year for 3 weeks each time has not had any problems at border as yet.

Be sure to have a flight out you can show them...

No problems.

What you or a friend have previously done for the past 20 years has very little relevance to what can be done today.

My neighbor has been coming and going every month for at least 16 years never had a problem but he has a lot of history

Suggest you get the METV multiple entry tourist visa from your Thai Embassy or Consulate in Canada.

With planning you can get up to 9 months of entries.

The METV is issued and valid for 6 months of entries into Thailand.

Nobody can really answer this as each entry is at the discretion of the immigration officer you will stand in front of